Trouble with GNOME and just about every type of file? It's the mime.cache!

I recently upgraded my machine to GNOME 2.26 (not sure if that's the culprit or not), but then all my nice icons disappeared and gnome wouldn't show any images or open any documents.

After scouring through some strace logs, I noticed a juicy looking set of files /usr/share/mime/mime.cache and ~/.local/share/mime/mime.cache. I deleted both of these, rebuilt the former with

sudo update-mime-database -vV /usr/share/mime

and presto, everything was golden again.