In an interview with Eurogamer, Fallout 3 lead producer Jeff Gardiner reveals that the Broken Steel downloadable content (Broken Steel DLC) due out in March allow players to take their character all the way up to a very-difficult level 30 top-out.
Along with the promised raise in the level cap to 30, Broken Steel also removes the ending for the game, allowing players to continue on in their adventure rather than having to deal with those pesky ending credits. "Along with removing the game's 'ending' with Broken Steel, we figure raising the level cap would allow them to [enjoy the game for longer]. We plan on raising it to level 30 - but it will be a long, hard climb to get there!"
[SOURCE]