Beginning on or about December 27, the app started creating file names that are exactly one year in the future. It's not getting the creation date wrong, that's just fine. But Photo Booth is now giving files names like 2010-12-29 at 11.00.
It's not the end of the world, but if you are looking to find a file by date in the name, you're sure to be confused. The bug appears in Snow Leopard, and I haven't been able to determine if it appears in other, older versions of the OS.
If you want to check the bug for yourself, take a snapshot with Photo Booth, and then look inside the Photo Booth folder inside the Pictures folder in your user directory. Let us know what you find.
Perhaps Apple should re-name the app "Time Machine II."
[Thanks to Oliver for the tip]