Update (2006-07-12): I do not endorse this technique. I hate it (see the "It simply drives me nuts" bit). I am merely documenting it to expose those people who use it.
This is what I call the "CSI" (not the TV show) technique - Change, Stall, Intimidate:
First, change the topic: "I think that's a very good question. It certainly raises some interesting issues related to what I said before."
Second, stall by talking about what you said before, for about 2 minutes.
Third, intimidate the person who posed the question by asking "Does that answer your question?" By this time, the audience is so bored that that person will not have the guts to pursure further questioning, in order to save the audience from listening to junk for another 2 minutes. However, if that person is somehow not discouraged and persists, say "Now as I said before" and repeat the "stall" step. Alternatively, s/he would have forgotten his/her original question by now.
It simply drives me nuts when I'm in a meeting and the speaker uses this technique when they clearly have no clue (I'll blog on other techniques used to say nothing, some other day). But from what I can see, this works like a charm. And now you know how to do it and sound intelligent too - great for those "strategic" business meetings that we all inevitably find ourselves in.