While "material promoting or encouraging proscribed drug use" has been replaced with more fictional drug references, Pete Hines tells Joystiq that "nothing else" has changed, including the over-the-top violence we've been enjoying in the screenshots. Full statement from Hines after the break.
"The chems in the original Fallout used fictional names ... Buffout, Jet, Rad-X, etc. Those all appear in Fallout 3 in exactly the same way as before.
"We had added a new chem to Fallout 3 and had given it a real-world name, Morphine. Questions were raised about the use of that real-world drug, not only in Australia, but other territories as well. We decided there was no reason it needed to be named that and it should be a fictional name like the other chems, so we changed it to "Med-X".
"That's the change we made in response to those concerns, nothing else."