Hi Bob,
Sorry for taking a while to get back to you, Kristian and I have been busy catching up since getting back, and wanted to make sure we got the chance to discuss the subject carefully before replying.
As far as we can tell, an unmodified Compiz should "run" on the device fine so that gives us a good start. Emulating the matchbox and hildon functionality doesn't sound very complicated, however from what I have seen you have a title bar for applications, and for this to be shown for each application a Compiz window decorator would have to be written that would emulate this functionality.
Kristian and I don't think something like Cube will work out well on the MID where you have one fullscreen application per viewport. In the case where you have either 2, or say upwards of 6 applications, the cube would become either flat or difficult to work with, respectively. We've tossed around some ideas for making something that makes more sense, but it will take some experimentation.
Making current Compiz features (i.e. Zoom, Coverflow) work on the MID should just be a matter of tweaking them to function in a nice manner, but nothing major.
It also seems like a simple settings manager for Compiz would have to be made to let the users tweak which effects are used.
Using an OpenGL canvas toolkit + Compiz right now is a problem, but we spoke to Kristian Hoegsberg about this at UDS, and he is landing a fix in upstream X/DRM/Mesa "any day now" to support redirected direct rendering, solving the problem. Intel graphics should be the first supported driver.
All in all, Kristian and I think with around 250 hours of combined work we could have it all working quite well, and demos of course before then. It could conceivably be a bit lower, or a bit higher if we run in to hardware issues, but in general 250 seems reasonable.
Regards,
Robert and Kristian