Lennert Regebro is one of the guys who did Five for the Zope and Plone world. He's smart, fun, accessible, and seems to live out the ideals of open source. He's famous for talks on the mistakes his frameworks of choice have made, and enjoys sharing it with the new kids like Django, Pylons, and TurboGears. I'm of the firm opinion he should run classes/tutorials at the next Plone/Python conference.
I also bumped into Christian Theune, a German Zope/Plone guy who isn't just smart, but also good to be around. Wish I had found time to eat dinner with him again.
Calvin Hendryx-Parker made his presence there known too. He's another sharp guy and is part of Six Feet Up. Which reminds me, I need to look into some Python hosting.
Note: Lennert Regebro's role in Five has been updated.