These are RF based, not IR like the Nikon wireless system so they do not require line of sight and they work over longer ranges.  Powered by a couple of AA batteries that are included in the box.  Got two of the Flex TT5-Nikon tranceivers.  The first generation Pocket Wizzards were dedicated as either transmitters or receivers, but these can be used either way (but not both ways at the same time).  Also got a Nikon 10 pin to Pocket wizzard cable.  This allows remote shutter release. 
12 Nov 2011 - very poor customer service (see footnote 1, footnote 2, footnote 3)
With one unit on the camera and the other on the SB-900 not only do you have remote flast triggering, but also the FP flash sync mode works, i.e. you can use all the shutter speeds including 1/8000 second.  So far I have not been able to use them as a wireless remote shutter release.

IMPORTANT - Open Antenna The antenna on the Flex TT5 must be opened fully in order to have a useful range. With the antenna in the closed position the range from a Flex TT5 to the MC2 is about 5 feet, with it open it's much greater.

IMPORTANT - Wheel retracts locking pin The wheel that clamps the FlexTT5 to the camera also raises and lowers the locking pin.  If you couple two FlexTT5 units together the locking pin is spring loaded and will snap into the other unit and they will not come apart until you retrace the locking pin by turning the wheel to the right on the top unit.  You can see how this works by turning the wheel on the bottom unit

Working Setup

Camera Top Used for Remote Shutter Release	Camera Top Used For Normal Shutter Release Power Tracking on E640
Channel 1	Channel 2
ControlTL Transmit Ch 1	ControlTL Transmit Ch 2
Standard Transmit Ch 2	Standard Transmit Ch 2
ControlTL Receive Ch 1	ControlTL Receive Ch 2
Standard Receive Ch 1	Standard Receive Ch 32
On: Basic Trigger	Off: Basic Trigger
Power Tracking: Full Manual	Power Tracking Center on ISO & Aperture w/First Shot
Remote Flex TT5 is in default config Hold TEST while power on, wait for: 1, 2, 4 LED blinks.

If the E640 is set to plain CH 2 and the MC2 is installed the E640 manual flash power up/dn buttons do not work.
If the E640 is set to control C-TL 02 then the power can be adjusted from the camera or using the E640 buttons.

Note: You can fire the E640 by pressing the TEST button on the FlexTT5. BUT sometimes it takes a strong press of the TEST buttom to make contact. That's to say the quality of the TEST button is not as good as it could be.

Channels

There are two channels on each unit (OFF - Ch1 - Ch2).  Each channel can be configured using the Utility software, a computer and USB-A to USB-Bmini cable.
The parameters are:
Channel numbers
    ControlTL Transmit
    Standard    Transmit
    ControlTL Receive
Flash
    Speedlight: Trigger or i-TTL
    Remote Studio Controls
        Remote Beeper: no change on wakeup (disable on wakeup, enable on wakeup)
        Remote Optical Trigger: no change on wakeup (disable on wakeup, enable on wakeup)
HyperSync/HSS
    On/Off HyperSync Only (Diable HSS/FP)
    HSS/FP Begins at (HyperSync Ends): (1/250 to 1/1250)
    HyperSync Flash Duration for Standard Channels: (1:Fast to 10:Slow)
    On/Off Manual HyperSync for Standard Channels
        Manual HyperSync Offset
        -1600 to 0 to +200 slider
    HyperSync for this FlexTT5 as Receiver
    AC9 Flash: (list of model numbers)
    P2 HyperSync Flash Duration (1-Fast to 10-Slow)
Power Tracking
    Mode:
         Full Manual,
        Center on ISO & Aperture w/First Shot,
        Center on ISO & Aperture - Set Both Below
        Center on Aperture Only - Set Aperture Below (aperture selection box)
        Center of ISO Only - Set ISO Below (ISO selection box)
        No Change (Trigger Only)
Modeling
    On/Off Modeling Light Control
    Control Mode: (Camera Wake, AF Assist)
    Modeling Light Auto Track (active or some % of full brightness)
    Modeling Light Sleep (always on or sleep after nn seconds after cameera sleeps at % brightness)
Sleep
    On/Off Remote TTL flash sleep Mode (always awake or nn seconds delay)
    On/Off Local Flash sleep mode (always awake or nn seconds delay)
Misc
    On/Off: Basic Trigger
    On/Off: Transmitter Only
    On/Off Disable Shoe Communications
   On/Off: SpeedCycler

Tools (gear icon in lower left)
Utility Updates
    On/Off: Check for new PW Utility updates every [14] days
Firmware Updates
    Check for FW updates every [14] days
    Select:
        Auto Download
        Notify when available
        Never download
Yes/No: Beta Test
Device Inventory
    Device     Serial             Version                Loader
MC2 US     M2Unnnnnn    2 (build 200)    3 (build 0)
TT5N US    5NUnnnnnn    3 (build3)         2 (build 7)
TT5N US    5NUnnnnnn    3 (build3)         2 (build 7)

Broken Foot

Dropping the camers+Pocket Wizard on the carpeted floor resulted in cracking the plastic foot on the bottom of the TT5 Pocket Wizard.  This is an assembly (probably there are different versions for Nikon and Canon flash hot-shoes) so can easily be replaced.  By rotating the knurled knob used to lock the foot to a camera 4 (+) screws can be removed, then the assembly can be moved a little but it is still restrained by the flex flat cable. The two black ears clamping the flex cable need to be moved away from the assembly to free the cable.

Adjusting Exposure at Camera

This is a great feature.  After turning on the Pocket Wizard then the camera and making the first exposure (in manual exposure control mode) fixed shutter speed and f/stop) and looking at the image on the back of the camera, you may want to change the exposure.  This can be done by pressing the exposure compensation button just behind the shutter release and while holding it down turning the rear knob to change the EV correction.  As the knob is moved the camera changes it's aperature by 1/3 f/stop AND the strobe changes it's light output in the same direction by 1/3 f/stop.  So each click of the knob results in a 2/3 f/stop change in exposure.

Patents

5359375 Microprocessor programmable digital remote radio photographic control, James E. Clark (Lab Partners Associates, Inc.), Dec 3, 1992, 396/56 -
7016603 Wireless communication module,  James E. Clark (Lab Partners Associates, Inc.), Mar 21, 2006, 396/56 -
7133607 Wireless communication activation system and method, James E. Clark (Lab Partners Associates, Inc.), Nov 7, 2006, 396/56; 396/59; 396/429 -
7437063 Wireless camera flash synchronizer system and method,  James E. Clark (Lab Partners Associates, Inc.), Oct 14, 2008, 396/56; 348/211.2; 396/59 -
7702228 Wireless camera flash synchronizer system and method,  James E. Clark (Lab Partners Associates, Inc.), Apr 20, 2010, 396/56; 348/211.2; 396/59 -
7764875 Wireless communication system and method for photographic flash synchronization, James E. Clark (Lab Partners Associates, Inc.), Jul 27, 2010,
7783188 System and method for maintaining hot shoe communications between a camera and a Wireless Device, James E. Clark (Lab Partners Associates, Inc.),
7880761 Wireless photographic communication system and method, James E. Clark (Lab Partners Associates, Inc.), Feb 1, 2011,
7970267 Wireless camera flash synchronizer system and method,  James E. Clark (Lab Partners Associates, Inc.), Jun 28, 2011, 396/56; 348/211.2; 396/59 -

Uses Insulated Gate Bipolar Transistor(s) to make and break the High Voltage circuit between the flash tube and the energy storage capacitors.  This allows contoling the flash duration and saving the charge in the capacitor bank.  Earlier designs dumped all the energy in the capacitor(s) which in addition to being wasteful makes for a much longer recycle time.

Triggering with Pocket Wizard MC2 receiver (one of the new advanced feature units) and FlexTT5 in the camera hot-shoe.

The 640 does not (and can not) support FP high speed sync like the Nikon SB-900 hot-shoe flash.

This unit uses Power Pole connectors in the standard ARES configuration that preserves the Hermaphroditic property.  That means an extension cord has the same connector on both ends.  Since the battery also has these Power Pole connectors it can be used in any "12 Volt" application with power poles.  For example the Power Pole to Cigarette Lighter Socket cable would work or any of the radio specific cables such as the VPA-2577 for the PRC-25 or PRC-77 radios.

SC-28 Extension Cord

Diffuser

The Parabolic Light Management (PLM) system uses specially shaped umbrella ribs rather than using a rain unbrella, also there are a lot more ribs to better control the shape.  The claim is 16X more light because it's an optical system.  There's also a white diffuser that makes this into a very powerful light box, or you can think of it as a shoot through umbrella backed by an optical system that makes it much brighter.

The hollow tube connected to the ring mount should be positioned so that it's far end is flush with the end of the short larger tube at the top of the umbrella, like if you pushed it aginst a wall.

51" PLM Umbrella

Notice light on floor is much larger than umbrella diameter.

86" PLM Umbrella

The circle of light on the floor is about the same diameter as the umbrella (7'+).
There are some shadows.

Einstien E640 Paul Buff 22" Spun Aluminum Parabolic Reflector "Retro Laser" being used with the StackShot for macro focus stacking.
The box attached to the light stand is the Paul Buff Vagabond battery powered 120 VAC power supply.  When the line cord is plugged into this supply the studio strobe can be used outdoors.

The circle of light is much larger than the 22" dish and it's harsh.  Note the floor is burned to white directly below the reflector.
Light Table The light table was showing surface scratches.  By taking a photo of just the table with no subject using the same manual exposure as for a subject the below image was discovered.
Only the left bottom strobe was firing.	After rotating the right bottom strobe 180 degrees so that it's photo sensor was facing to the front it started working.  Adjusted both bottom power levels to about half way.  E640 with 54" umbrella and diffuser set to full power.  Camera M-mode, ISO: 200, 1/100, f/29 18-200 zoom lens.

5' x 7' Black or White Background

Additional comments:
6) Utility program (ver 1.35)  displays the firmware version in a format that's different than what's displayed in the literature and when downloading new versions.
7) Most of the press releases on the PW web page do not have release dates.
8) The LED on the MC2 receiver for the E640 (a) is hard to see if it's blinking, (b) is a TEST button, but there's no description of what it does.
9) the effect of holding the TEST button on the FlexTT5-Nikon then powering up and waiting for the 1, 2, 4 LED blink sequence is not clear.  I think it reverts the units to factory default settings, i.e. channel 1.

10) It's not clear how these units work in terms of being a transmitter or receiver or both?
11) is FP-sync supported with the E640