343 just announced a new pack, Cahmpions Pack I believe. It contains two maps, Pitfall, a remake of The Pit from Halo 3, and Vertigo (?) an all new one, two week exclusive access to a new game mode, Ricochet which is like Grifball mixed with Slayer and you can throw the ball in the goal to score (it actually looks really good fun) and some new armour sets, weapon skins and stances. It's 800MSP for all of it or you can buy it all seperately for varying prices.|
I would normally have preferred an extra map to the other stuff but the skins do look really cool, you can make yourself look like an ODST!
XBL/ PSN/ Steam/ NNID - MatMan562