ported to OSX. not tested; almost definitely needs more work.

hey Mark,

rearchitected this to make it (hopefully) work cross-platform using the Automator to add a context menu entry and Cocoadialog in place of Gtk. not yet tested, but if you want to ensure I haven't broken it on Linux/Windows, that wouldn't be a bad idea... (I'll check myself later on).
Sorry, I don't think I understand... if it's commented out, it's not doing anything. And if this code wasn't commented out, what is in the /tmp directory that it would be cleaning out?