The blogging platform Journalspace as of which I never heard of before today has lost all data in its data base from a disgruntled employee wiping out the data base upon his leaving.
From the journal space blog
It was the guy handling the IT (and, yes, the same guy who I caught stealing from the company, and who did a slash-and-burn on some servers on his way out) who made the choice to rely on RAID as the only backup mechanism for the SQL server. He had set up automated backups for the HTTP server which contains the PHP code, but, inscrutibly, had no backup system in place for the SQL data. The ironic thing here is that one of his hobbies was telling everybody how smart he was.
This doesn't excuse what happened, though: I should have taken a better look at what he'd left behind, and fixed all of the things that needed fixing.