Halo 4 DLC formally announced, check out the trailer
From 343 Industries:
The Halo 4 Crimson Map Pack is the first of three Map Packs from the War Games Map Pass. Currently scheduled for release on December 10, 2012, it will cost $10.00 USD or 800 Microsoft Points and consist of three maps offering something for everyone, including a variety of designs, spaces for tight firefights or vehicle warfare, as well as 8 new achievements and a new Crimson DLC playlist.
Extraction, a 5 vs. 5 objective-based game type where opposing Spartan teams are tasked with extracting assets from various sites around the map, will also be available for the first time in Multiplayer Matchmaking, on the same day that the Crimson Map Pack becomes available.