Last Monday, Bungie released 5 new multiplayer maps for Halo 2. The newly named maps are Gemini, Relic, Elongation, Terminal, and Backwash. They are all incredible and are well worth the $11.99 to download them online. More information is available here.
Yesterday, Bungie updated their multiplayer playlists to include the previous 4 maps (Warlock, Containment, Sanctuary, and Turf) in their core playlists. The reason for this delay was that they were just made available to everyone for free recently. They also fixed a few other minor things, such as having a Banshee on Ascension Rifles.
All in all, a very important and very great release by Bungie!