Thanks to Doug Napoleone's work, the PyCon schedule planner is back this year.
You can use it to lay out your conference ahead of time: click on events and talks you'd like to attend, and then export your selected events in iCal format or print a customized schedule.
Your choices are saved on the PyCon server, and the organizers can see a summary of the popularity of each event. This lets us compare the popularity of various talks. At last year's PyCon, we swapped a few room assignments when a talk scheduled for a smaller room proved unexpectedly popular; I bet we'll do the same this year, too.
Known bug: the popups don't work with Safari 3.0.4 on Leopard; bug #247 describes the problem.