Bethesda has released the next patch for Fallout 3, bringing it to version 1.4.0.6. I'm not really sure why there are so many numbers, but whatever. From GStaff:
Today a new update (v1.4.0.6) is available on Xbox LIVE and Games for Windows LIVEUpdate 1.4 Notes (PC and Xbox 360).
It's a small update in preparation for the game's second DLC, The Pitt, which is slated for release this month.