Ooh, interesting. We know anything about the main antagonists? Perhaps another branch of the Enclave?

Edit: Thinking about it, this essentially gives them the ability to completely start fresh in a non-lame way, since transportation by other means than foot is really rare. The Brotherhood of Steel may not be present over there and such.

Let's hope they run this in a good direction, as this feels like the main reason they would switch coasts. Should give them tons of leeway for creative license... =)

I imagine that radiation around D.C. would be enormous, as it would've been a primary target for the opposition in the war.