If you boot up Halo 3 today you'll notice an update to the matchmaking mode. Bungie say they are busily working on new gametypes, modes and new hoppers, but for now you'll just have to be content with the following changes:

* Big Team Battle matches are now 16-player affairs.
* In the Team Slayer playlist, the appearance of Shotty Snipers has been greatly reduced.
* Now, when players veto Shotty Snipers, the game that results from the veto will not be Shotty Snipers.
* In one-sided VIP matches, the attacking team will now see a waypoint for the VIP they are hunting.
* In Lone Wolves, Slayer gametypes will appear more frequently.