Microsoft has announced that the next map pack for Halo: Reach, dubbed Defiant, will be releasing at some point during March. They also revealed that a development studio called Certain Affinity, not Bungie, will be creating the content.
Three new maps will be available: Condemned, Highlands and Unearthed. Each will offer its own distinctive feel. Condemned will be used for 6-12 player multiplayer, Highlands for 8-16 multiplayer and Unearthed can be used for Fightfight matches.
It will cost 800 Microsoft Points when it launches, and it will grant you access to another 150 Achievements Points to bump up your Gamerscore.