The Cyanogen team was able to get CyanogenMod v6.1 booting on the T-Mobile G2 today! Although this isn't a permeant solution, it just shows the progress is going well.
http://www.youtube.com/watch?v=piyJ_e1nZC0Basically what Iím doing is temprooting and rebooting all of userspace with CM on the sdcard. Gonna keep refining it while the really persistent and smart guys from #g2root keep working on a permanent root.
Source: T-Mobile HTC G2, Meet CyanogenMod: Video Of CM6.1 Booting On Cyanogen’s G2 | Android News, Reviews, Applications, Games, Phones, Devices, Tips, Mods, Videos, Podcasts - Android Police