Information update: there seems to be a bug that been around since Ubuntu 11.04, which also affects some Debian machines, using Nautilus.
Basically, Nautilus automounts the camera drive, then shotwell can't get a lock on the camera drive and crashes.
The workaround seems to be to first plug in the camera, then umount the drive from Nautilus. Then start shotwell.
Read the bug report here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=610207