This message was touch typed on two Apple magic trackpads and some hacked-up software based on PyMT. I can't use modifier key taps yet like shift or return (and of course I keep doing those by mistake), it's rather small, and there's no mouse or other gestures yet, but it is just about useable. Next step is ignoring input when all fingers are resting on the surface.
It runs on ubuntu maverick and generates key events using uinput, which means that ubuntu sees it essentially as a normal keyboard. If and when I make it work nicely, the plan is to make a bootable USB stick so I can boot my laptop into Linux and have the laptop function as a bluetooth keyboard and host -- that would mean that laptop + trackpads are seen by any bluetooth-enabled computer as an ordinary keyboard (and proabably mouse also).
I initially thought I wouldn't want gestures other than taps, but I may change my mind due to small size of keyboard -- might be handy to have normal keys take up the space currently occupied by the function keys since space is limited. I'm surprised by how useable it is already for typing though! A bit awkward, but certainly just about useable. In fact I think after resting fingers and modifier taps, perhaps the next most useful thing may be some kind of typing correction that fills the same role as the feature the touchstream had where it would emit backspaces and retype a correction, based on a dictionary or English spelling model. Maybe not as much fun as pointer motion though, so maybe I'll do that first