There have been framerate issues, but they were all due to the CPU handling all the sound not being optimized for the dev kits. And in HALO\'s case(This game was really suffering from some bad framerate problems), CPU handling all the sound, not optimized for hte dev. kits,
and Networking all slowed it down. The CPU was just doing too much at E3.
All of these problems will be fixed by launch, though.
Bungie has confirmed that HALO will be running at a smooth 60fps at launch., even in multiplayer mode... If they can get that game running at a silky smooth 60fps, I dont see why any of the other games cant.