If the last time you looked at the SIGCSE 2009 events was when you did early registration (and thank you for that!), you may have missed some additional activities to participate in.
Sun and Pearson are teaming up for a Pre-Symposium Event on Wednesday on Java Technology. They'll be presenting new curriculum that's part of the Sun Academic Advantage Program. See http://www.cs.arizona.edu/groups/sigcse09/presymposium.html for updates on this and all pre-symposium activities.
The Alice 3 workshop (#16) was overwhelmingly popular -- the wait list was large enough to fill another workshop. Wanda Dann and Steve Cooper have kindly agreed to offer a second Alice 3 workshop on Saturday evening from 6-9 pm. You can register for Workshop #37 on the SIGCSE 2009 Registration Website.