1080i and PS3 problems?
According to this IGN article, PS3 games that run in 720p will not upscale to 1080i for TVs that support 1080i but not 720p (like some HD CRTs). Instead, the 720p game will be downscaled to 480p or 480i.
The Xbox 360, of course, will upscale any 720p game to 1080i.
I feel sorry for anyone that buys a PS3 with a TV that doesn't accept and display 720p, or at least upscale it to 1080i (my CRT will take 720p and upscale to 1080i, but I just have the 360 set to 1080i and let it do the work).