To the skeptics; how many deaths are there in Halo 3 matchmaking? That's all player vs. player, with firefight, the multiplayer is killing covenant. Plus, firefight-esque gametypes are very popular (-blam!- zombies, left 4 dead to an extent, GoW Horde mode). It will be really popular. I'm convinced 7 billion is reachable, but it's not going to be easy at all.
We'd need ~350k grunt kills/day I think..
[Edited on 09.19.2009 5:38 AM PDT]