(Adapted from a comment I made to someone else's posting at Hacker News:) When I've been at business events where I don't know anyone, I don't even bother trying to introduce myself to the "important" folks. (Cf. Luke 14.7-11.) I seem to have enjoyed such events the most when I've looked around for people in the same boat as I; introduced myself; and asked them about themselves. I'll interject bits of my own story when appropriate, but I try to keep the conversation focused mostly on the other person. After a few minutes, I'll smile and say, "hey, it's been great talking to you," maybe swap business cards, and move on - rinse, repeat.
If I can play matchmaker and help get multiple new acquaintances talking to each other, so much the better.
Some open-ended questions I've found useful: How did you end up at X company? What got you into X field? What challenges do you see ahead for X field?
I figure life isn't a snapshot, it's a movie; if I keep going to these events, and keep focusing on making others feel welcome and included (even if only by me), then in due course I'll end up getting to know the movers and shakers.