The guys over at PC World have compiled a list of the phones they believe are getting the Android 2.2 (Froyo) upgrade. Much of this has not been announced officially by the manufacturers or carriers yet, and should be considered with a grain of salt.
Definitely Getting 2.2:
Nexus One
Motorola Droid
HTC Incredible
HTC EVO 4G
MyTouch 3G / MyTouch 3G Slide
HTC Desire
Maybe Getting 2.2:
Motorola Devour
HTC Droid Eris
HTC Hero
Motorola Backflip
Not Getting 2.2:
T-Mobile G1
Samsung Behold II