Below, a video demonstrates Android running successfully on the HTC Touch Pro2, which is normally seen sporting the not-quite-as-fashionable Windows Mobile coat. It looks very smooth, and with that slide-out keypad and 3.6-inch screen, could be what you've been after.
A HTC Diamond2 port for Android didn't work nearly as well, but judging by the video Touch Pro2 owners sick of Windows Mobile 6.1 are in for a treat. Of course, the usual caveats of breaking the warranty, risking blowing up your phone, blah blah blah, all still apply - but we trust you. [PocketNow via Android Community via SlashGear]