Fallout 3 Forum Tidbits

The Fallout 3 devs sure loosened their tongues a bit lately, now clarifying some of the stuff about dialogue (and how little we've seen of it). First community manager Matt Grandstaff forwards something from lead designer Emil Pagliarulo.
Anyhow, I just chatted with Emil on the matter and he had this to say:

We don't have full dialogue options for characters with low intelligence. That is to say, you cannot simply "Ughhh" and "Agghh" your way through dialogue. That said, there are some Intelligence-specific dialogue options in the game.

That's all I've got for now
Then Emil Pagliarulo talked on dialogue in general.
I know you guys haven't seen a lot of dialogue, but I really don't think you'll be wanting for options in that regard. The dialogue trees are pretty detailed, and there are plenty of response options, including those that check for skills, perks, S.P.E.C.I.A.L. attributes, etc.

The one screenshot with dialogue that we did release -- shows a guy with a couple of "do you want to come with me" type of responses -- is actually an example of the smallest set of responses. The majority of NPCs have several more.

In general, what you can say depends on who the NPC is, all your combinations of stats and skills, events that have transpired, how you want to respond (different "attitudes" or "voices"), and more.