The game is due for fall 2011, probably october like Forza 3 as september is for Gears 3 and the next CoD will be probably be out by november.
Well, renders and footage have been around for almost a year now, of course it has already been analyzed to death in different threads. This whole talk about Forza Kinect really is LTTP, especially now that we have more recent direct-feed HD footage...
Off-screen footage, HD or not, is still off-screen footage. Every game will look better off-screen. I'd even go as far as to say the poorly compressed direct-feed footage better represent the demo than the off-screen footage because you have the real look with the real colors, lighting, etc... and not some overexposed image.
Edit :
Obligatory pic with the superior European/French collectors editions and the Forza 1 press kit as a bonus ! :-D