Penetrated MacBook

So someone managed to take over my MacBook. He had me completely owned. Full access to my screen and all. I hopped out of the shower just in time to see him take control of my mouse and start jerking around. He opened my calendar (Why? I don't know) and I immediately slammed my thumb down on the power button. A prompt about the shut down popped up and he tried to click cancel, but I was hitting the hardware power.

Anyway, I've never really worried about protecting OSX until now. Has anyone heard of something going around that would allow this kind of access? My best guess is I was originally compromised a couple weeks ago on my hotel's wireless in Chicago. I've changed my passwords to all of my accounts and I'm re-installing OSX now, but I'm wondering if anyone has heard of anything going around and what the best way to protect myself is. Obviously, I'm computer literate and not a complete dumbass, so the typical common-sense counter measures were not the failing point.

Ideas?