An email from the Full Disclosure security mailing list indicates that the MacOS X screen saver will quit itself thus exposing the Macintosh desktop.

There is no patch to fix this at of right now, and the individual who published it says that he gave Apple 3 days before posting it to Full Disclosure (although you really have to wonder about the judgment of waiting only three days right before a national holiday.

This will only affect users whose machines are in public with screen savers as their basic protection and won't give you trouble if you log out or shut down and require a log in to access the machine. Further, locking your private files and disks in an encrypted disk image when you go away from the machine will protect most of your data.