This is something I've been working on on-and-off for a while... But I've had quite a bit of spare time to work on it as I'm 'between jobs' at the moment....
- Uses PocketHAL 0.4beta
- Currently only supports 565 displays
- No gameplay/physics yet - it's really just a test of the 3D engine
If it works, it should look like this:

Demo is here:
http://www.bluescrn.net/PocketPockets.zip
(there's no installer - just copy both files to your PPC and run the exe)
Run it at your own risk.... It works fine on my iPaq, but other than that it's completely untested, and PocketHAL is also still beta...
I get between about 48 and 56fps on my iPAQ 3870. But haven't got anything else to test on...
There's still a fair bit of room for optimization, as it's almost all in C (other than clearing the screen...)