Is this a system you have physical access to? Chances are you could use something like recuva or encase to recover a wallet.dat file since in most cases "deleting" something doesn't really delete anything at all... Depends on the filesystem/OS/etc of course, and it certainly wouldn't count as "touching" the system since you're only reading data.
As far as I know, my utility for recovering bitcoin private keys
is probably still the best option - though it doesn't recover any other information from the wallet.dat like account information, and obviously it can't recover any external databases used to store account details. A lot of recovery tools are based on file magic numbers, and BDB doesn't seem to have any obvious ones. (Of course, that would only help in the unlikely event the original post isn't a troll.)
This idea was conceived on the somethingawful forums. One member outlined a plan to make this post if someone could get him a mybitcoin logo. So no, its not Tom Williams.
But there's stairs in this thread.
Where? I don't remember seeing any mention of this, but I haven't looked hard and it sounds plausible...