There's some headway on android on the titan (not by me, just passing it along...)
If you've been out of the loop, the Touch/Vogue guys have
http://it029000.massey.ac.nz/vogue/
Which is pretty much fully functional - you get a G1 phone with half the screen
You can run that latest image on the titan as well, and everything works great except the buttons/keyboard.
There is a replacement zimage (basically the OS bit) that implements the keyboard/buttons correctly, but IMHO that image seems to have other issues, like not detecting the battery correctly, and leaving the button backlight on when its powered off.
xda thread for the titan:
http://forum.xda-developers.com/showthread.php?t=341903
Hopefully they'll build the titan-button-aware version off the latest vogue zimage soon.
Pretty nifty though, if you're looking for a change of pace.