Joystiq has posted their preview of Fallout 3. Highlights:
On similarities to Oblivion:
From the first moment you lay eyes on Fallout 3, you can't help but start drawing similarities to Oblivion.
Yet despite the fact that the same 75 person team worked on both games,
it quickly becomes apparent that this is more than just the "Oblivion with guns" some fans have been worried about.
On the technical aspects of the environment:
The ever-present rubble is especially impressive and players can always
create more through a system called "parallax occlusion mapping" which
lets practically every surface be potentially filled with bullet holes
or warped by explosions. "Destruction is the new trees," Howard quipped
during the demo, referencing Oblivion's use of SpeedTree.
On story themes:
Howard said the story outside the vault will focus on themes of
sacrifice and survival. What you choose to sacrifice and how you choose
to survive has a big effect on how the game turns out.
Go and read the whole thing here.