I just got my Pre2 all nice and Sprint-ified, and am trying to put stuff back on /media/internal/, the USB drive. I copied a bunch of stuff over there, but none of it shows up. In webOS 1.x you could run "stop fileindexer," delete the media DB, then restart fileindexer and it would . . . well, re-index your files for you.
There is no "fileindexer" service in webOS 2, though.
What needs to be done to get the pics and music to show up?