I haven't interacted with him much, but Vinge was a speaker at this year's main North American AI conference (AAAI), and was impressively engaged. Unlike many famous speakers he didn't just fly in for his 2 hours and fly out again, but attended a whole bunch of sessions for several days, and he was asking pretty intelligent questions. Mostly normal questions about the specific research at hand, too, not singularity-related questions or "how will this research help the robot revolution". ;-) Seemed like a very down-to-earth guy; I don't think most of the researchers who got asked a question by him realized that he was a famous sci-fi author at the time.