Has anyone found a solution, or an idea of where this is coming from yet? It just happened again using IDE version 1.0.4 and uploading a sketch. I have a late '08, 17" Macbook Pro running 10.8.3. My panic report is just as uninformative as the one already posted.
Another detail, this crash always happens when uploading to a board. In my case, a genuine Arduino UNO R3. It has not happened with the Leonardo yet.
When my Mac crashed this morning, I had only the Arduino IDE and Google Chrome running, in addition to the normal Mac processes. In order to eliminate the possibility of another USB device confusing the OS, all external devices, other than the Uno, were disconnected.