Nice post; thanks for clearing that up.
That Cache.db-wal is, indeed, an elusive and mysterious little critter that I'd be deleting constantly if it were on my deuced Mac(hina).
I took a quick look for it (not Cache.db-shm, though) - knowing full well that I wasn't very likely to find very much if you couldn't - and found out little more than that it apparently first appeared in OS X 10.8.3, that it is apparently an iOS item, and that it seems to have something to do with an SQL database.
The complete absence of details about its contents, though, is pretty disconcerting.
