Bethesda has announced today a good amount of DLC coming to Fallout 3 over the next few months. The content starts out with the G.E.C.K. (Garden of Eden Creation Kit) which is the basic editor for Fallout 3 and will be coming to Games for Windows users sometime in December.
"The release of the G.E.C.K. provides the community with tools that will allow players to expand the game any way they wish. Users can create, modify, and edit any data for use with Fallout 3, from building landscapes, towns, and locations to writing dialogue, creating characters, weapons, creatures, and more."
Secondly the first pack of console DLC entitled "Operation Anchorage" will be available exclusively for the Xbox 360 in January, with "The Pitt" and "Broken Steel" coming later in February and March.
• Operation: Anchorage. Enter a military simulation and fight in one of the greatest battles of the Fallout universe – the liberation of Anchorage, Alaska from its Chinese Communist invaders. An action-packed battle scheduled for release in January.
• The Pitt. Journey to the industrial raider town called The Pitt, located in the remains of Pittsburgh. Choose your side. Scheduled for release in February.
• Broken Steel. Join the ranks of the Brotherhood of Steel and rid the Capital Wasteland of the Enclave remnants once and for all. Continues the adventure past the main quest. Scheduled for release in March.