The first downloadable content pack in presumably a long list of packs to come for Halo 3 is available today from the Xbox Live Marketplace, Microsoft announced. The "Heroic Map" pack, as Microsoft and Bungie are calling it, will cost you 800 M$ Points...

"each map offers a unique experience. Standoff's symmetrical valley, with its entrenched bases and fields of boulders is ideal for mid-sized objective and Slayer game types, while Rat’s Nest’s vast, labyrinthine passages bring something new to the "Halo" multiplayer experience: an indoor vehicle paradise, strongly influenced by the Campaign mode, ideal for big team battles. Finally, Foundry is the ultimate Forge map – players can edit every single object in this voluminous industrial warehouse, place stairways, walls, bridges and tunnels to create an entirely new play space and build almost any kind of map they can think of."

The pack will eventually be made free of charge next year just prior to the next update, but this should offer any CoD4 deserters reason enough to jump back to Halo 3 for a bit of a slog.