Vector at Battleground: Halo was able to get in a few questions at Doug Zartman and managed to get an answer (of sorts) about the inclusion of a first-person perspective:
BG:H - Will there be a 1st person view mode at all? Even if it isn't polished? Kinda like how Tribes 1 was primarily a 1st person shooter, but had a shabby 3rd person view to keep some of the players happy.Doug - We've been giving it serious thought but haven't decided on the matter yet. If we do, we'll do it right. We try very hard not to do things half assed. If we can't do it right then we won't do it at all.
I'd call that a definite maybe on first-person.