Absolutely, freaking SWEET! This news just made my day.
Halo 720p on big widescreen TV is unbelievable. Now you can have that your 42" HDTV and have a quick 4x deathmatch just with one x360, since every portition of the screen is easily so sharp that you can see what you're doing. Wasn't really that usable in 480p. Also that game will look oh-so-sweet, no jaggies and high resolution will really make a huge difference, even if the models are the same old low-poly, low-res. Very similar to having pc version running with AA:
http://www.gamespy.c.../PC/halo/20.jpgMy guess: Bungie was asked to overlook the BC profile of Halo for x360. They tested it and they could allow it to run on 720p+AA, just allow, they didn't add any extra code or new textures. It's pretty obvious that all other games could be run in their full glory too, and should atleast be given an opportunity to do so, since otherwise it'd be MS favoring its own titles.
Other guess (less optimistic one): Bungie recompiled the executables for Halo 1+2, added the new features and other BC games won't be as glorious.
Anyway, I already see myself playing 720p AA Half-Life 2 on TV already. Wohoo
