Bungie is trying to take out Call of Duty 4 in the Xbox Live Activity charts and has released details on their March Playlist changes, which include "double XP weekends". The weekends will start this Thursday with the playlist Grifball (more details below), and as well as that changes have also been made to some of the downloadable content:

Downloadable Content Changes

-Fixed map exploit on The Pit
-Fixed map exploit on Construct
-Fixed map exploit on Epitaph
-Reduced Ranked Big Team Battle "Large party" size to six players and increased Big Team threshold to two*
-Fixed Spartan Laser occasionally falling through map on Sandtrap
-Fixes to matchmaking to allow more even leveling for players
-Disabled Mixed Skill restrictions for RBTB and Team Slayer**

New Playlists

We're introducing two Weekend Hoppers DoubleXP playlists this month, with the first hopper launching Thursday, March 6 at NOON.

Grifball, the game created by Burnie Burns of Red vs. Blue will be an unranked, weekend-long social playlist awarding DoubleXP to winning teams. We've slightly adjusted some of the rules for Grifball (unlimited round times make for unlimited griefing potential), but kept the game's core intact. You'll be able to go in with party configurations ranging from one to eight people. This playlist will be available from Thursday, March 6 at NOON until March 10 at NOON(all times Pacific Standard). I apparently forgot to mention that the Grifball hopper is being treated like a Tournament hopper -- a hopper where there will be prizes. Tournament prizes.
Beginning March 20 at NOON will be the return of Team SWAT in the Social, DoubleXP variety. Team SWAT is an old Halo 2 gametype where players have no shields, increased body health and do not have the luxury of radar. This eight-player maximum hopper will be completely Team Slayer focused with the SWAT ruleset. This weekend playlist will be available from March 20 at NOON until March 23 at NOON(all times Pacific).

Since they changed the BEATDOWN rules I am very dissapointed with Halo 3!!!

Dont be mad WOLF its just means you actually gotta work for a kill now!!!