I hope you're in the mood for yet another preview of Fallout: New Vegas, because UK website XboxHome has written up their own hands-on piece. A couple of paragraphs:
The combat system has been improved upon as well. Optional ammo types have been added to give another level of strategy. Additionally, melee weapons will include special maneuvers when attacking. Many of these special moves are only available with certain types of weapons and require you to have a certain skill level, thus adding more depth to the strategy portion of the game.
Another improvement that the creators are proud to reveal is the modification system for weapons. In the last game you could make a few special weapons, but beyond that you needed a higher skill or simply maintain the weapon to make it work to its full potential. Now it sounds like there is now ways to make weapons better through technology. Given the setting this seems like a natural step that should have happened a long time ago.