In case anyone else is interested in this, be very wary of playing with the gconf database, especially anything to do with the "osso media server" (e.g. /apps/osso/osso_media_server). I was trying to disable support for m4a, and when I tried tweaking one of the gconf keys, my N800 started going into a reboot loop. I'll have to reflash it. Good thing I didn't have any important data on there....

Edit: Oh crap! All my Maemo Mapper v2.0 test binaries! This sets me back another 2 months!

Just kidding.

: )