As we reported in October, ATLAS is short for Assisted Tactical Assault System and it's a "near-real-time player data and tactical guidance" supplement for your Halo: Reach multiplayer matches. What does that mean? Detailed maps of the game's multiplayer levels, including boring stuff like spawn and health pack locations, and the cool stuff like "near-real-time locations for weapons and vehicles." That means GPS-like pinpointing of your location while you play the game. You can find more data direct from Xbox at the Source link below.
There is one catch, however: While Waypoint will be free for all three platforms on December 10, ATLAS will run iOS and Android users $4.99 while Windows Phone 7 users get something to gloat about, with the app's $0 asking price.