Well, that much I do know... already been down that road with touch pro's "hardware accelerated graphics". HTC is well known not to utilize chip's full potential, let it be due to licensing or whatever reason there is.
After quick search on google, it seems that N1/Desire/iPodTouch3G/iPad all contain BCM4329, and seeing all the good devs coming over to Evo territory I'm having my fingers crossed that someone unlocks/writes a driver+app for that FM transmitter before this christmas
EDIT: ... given that the FM transmitter part of the chip is actually wired to the board
I've been dealing with various radios on linux with x86/x64 hardware for past 5 years, so I'll give Evo a stab and see what I can do with it