* Teen age gives you access to a few quests which will have an impact on how you are perceived within the Vault
* While travelling across the Wasteland, you can come across a few caravans, each heading to precise locations.
* There are three difficulty levels, as well as an "autolevelling difficulty" mode.
* A few new weapons : Cryolator allows you to freeze ennemies while you can hypnotize them with your Mesmetron. [these weapons were also mentioned in the NMA preview, though their functions unknown]
* Also a new perk, Daddy's Little Girl, which gives a Science bonus to female characters.

Choice quotes:
"Bethesda's last title, Oblivion, was a huge slice of freeform joy."

"[The prospect of Bethesda making Fallout 3 is] as close to a dream game as anyone has managed so far."

"[...]and there's a vociferous (and presumably faintly insane) minority that's convinced this game is a slight on the previous two and will simply be 'Oblivion with guns'."

"It seems that rather than be discouraged by the negativity, the team is spurred on by it."

New info (or at least info that I haven't seen before):
The Behemoth is based on some concept art that Adam Adamowicz drew. Originally it was to use a car battery on a chain as a weapon, instead of the hydrant.

Certain perks can only be taken by certain karma levels.