Very nicely, it seems, on the 6700 running WM6.
http://forum.xda-developers.com/showthread.php?t=343583
Ok, so now I really really love the 6700 again
I installed FTouchFlo_v1.4.1.CAB and HTCCube2.cab, soft reset, and started flipping cubes
All files from xda, and developed by all the great folks there, included here for ease of use. Consider it early alpha stuff, I don't think any of this is romable just yet but once it all stableizes it would make a great OEM.
Somewhat big download, 1.1MB zipped, > 5MB unzipped
Notes from others in this thread
? Problem: I installed the cube, and now my Contacts tab in HTC Home is gone!
* Resolution: Delete the registry key: HKLM\Software\OEM\MASD\QuickDial (then soft reset)
Also, only the HTCCube2.cab is needed for a fully functioning cube.
How Does It Work
Swipe your finger or the stylus up from the bottom (mid-screen) to bring up the cube. If you are using your finger, you'll probably have to press a little harder then you would think - mind those fingernails!. Pretty much it works like the touch.
HINT: Until you get the hang of it, try using your stylus to get the cube up, or to scroll in apps - it is a lot easier to get it to work with the stylus - the thing about FTouchFlo is you HAVE TO MOVE right away when you start a "swipe" - any pause at the beginning and the FTouchFlo app will decide you want to let the normal WM tap action happen.
So you need to practice that smooth "Pen/finger down and move" maneuver... once you get it, you'll have it. You can tweak the numbers in the setting file, but I'd see if you can figure out how to do it as is, first.
Issues/Support 
You can tell FTouchFlo which apps you don't want it messing with, you just need to add the app (by name) to the exception list, then soft reset.
Edit \Program Files\Touch Flo\FTouchFloConfig.txt
Good apps to add to the exceptions list:
S2U2 - so cube actions don't work when your screen is locked via S2U2
Notes - so you can draw in notes with ease
So add
Exclude:S2U2
Exclude:Notes
Then soft-reset
Known problems
If you use device lock FTouchFlo doesn't play well.
Screen align won't work with flow running - you'll need to remove the flow links from startup, soft reset, align, return, or some other mojo - I'll see if I can come up with some clean procedure for this, but if you suffer from frequent realigns this isn't going to work well for you
More on Alignment Not working - workarounds
As you probably noticed by now, you'll need to move some links out of the \Windows\Startup folder and then soft-reset to safely disable the FTouchFlo app and regain the ability to align your screen.
Once you've got your alignment fixed, you have to put all the links back in, and soft-reset again.
I'm thinking a safer way to run is to leave all the cube/tflow links out of the \Windows\Startup folder - just move em somewhere else. When I soft reset, I just run em manually once. That way, if I ever run into some weird need to realign screen, all I need to do is softreset, I can then align the screen, manually launch the TFlo app, and I'm good to go.
I can probably make a mortscript that sits in the startup folder, and after a minute or two launches the flo and cube stuff... that would make it load automatically, but still give me a couple minutes to align the screen after a soft reset. So far I'm not resetting all that often, so its no big deal.
Oh, and if you are using the cube and ftouchflo, you really don't need to run all those "preload" links in \Windows\Startup for the cube - the cube will work fine, just a bit slow the first time you see any "face", if you don't. If you never bring up the cube, you won't lose the half meg or so of ram preloading takes, either.
Keep an eye on the actual FTouchFlo development thread over at xda:
http://forum.xda-developers.com/showthread.php?t=338143