If you dug duking it out in Halo 2's futuristic construction site, Headlong, you'll be happy to hear that it will accompany the other confirmed maps in the upcoming Halo: Combat Evolved Anniversary. Now called "Breakneck," this classic map is still based around vehicular combat and Objective-based gametypes, but now features some additional cover added in some spots, and the old fashioned teleporters (that's so 2004) have now been replaced by man-cannons.
In addition to that, 343 Industries shed some light on the upcoming Halo: Reach Title Update, which is slated to drop on September 21. At first, you'll be unaffected by the patch, but on October 4 you'll see a "brand spankin' new playlist"--Beta Hopper--where all the changes will be featured. The playlist will feature 4v4 Slayer and Objective gametypes, DMR starts, and 85% bloom.
For a complete rundown of the beta playlists, head on over to the official site.