The new Fallout 3 DLC that's coming out looks a bit too scifi and not Fallout, but hey, whatever. Check out some info from IGN:

The liberation of Alaska was hinted at a lot during Fallout 3. What can we expect out of that simulated battle?

Anchorage the player will find themselves able to re-live the famous liberation of Anchorage from Fallout lore -- inside a simulation similar to one found along the main quest of Fallout 3. Once the player finds their way into the simulation, they'll be stripped of their resources and have to survive within the rules set up by the simulation's creators.

The Chinese red army is everywhere, and the player will first have to secure the surrounding mountain side and then fight their way into the Chinese base. The player will have to use a lot of their standard combat skills, along with several new tools that will only be available in the downloadable content. These include interactive Strike Teams under the player's command and unique armor, weapons, and other exotic gadgets.

The liberation of Anchorage must have taken place before the entire country was destroyed. How different will the art style be for this download?

Anchorage has a vastly different art style. It's taking place in the frozen north; so you have a very bright ice/snow color pallet. We've had a massive amount of art resources at our disposal, most of what the player will experience was created from scratch. We've also taken a lot of time to create a bunch of 'animation vignettes' to make the soldiers and other NPCs interact with the world in better, more convincing ways then anything we were able to do with the Fallout 3 main game.

You can go here to read some more and check out a load of screenshots. And, yes, there appears to be an energy weapon tank. And a gauss rifle.

Spotted @ Voodoo Extreme