I am currently working on a Windows Mobile 5/6 version of the game. It should be ready in a week or two.
Graphics will be minimal, both VGA and QVGA support is already done, and there will be no sound (as of right now). Multiplayer support is working right now, but limited to 99 servers max for some reason. Right now it runs pretty smoothly on an Axim x51v, so I guess you need at least a 600mhz processor and 128mb ram, but I have not tested it on anything lesser.
I will let you know how it's going.
-C