This morning I found out that about 6 months worth of data was deleted from my MySQL database hosted at Dreamhost (tell them I sent you). I had a script that was supposed to clean out certain database entries periodically depending on a validity response that I get from the Amazon web services. Well, something went wrong and that specific error code was returned for every item, so they were all systematically deleted. A good example of a bad software bug.
I notified Dreamhost, hoping they could restore it from one of their system backups. A few hours later it was done.
Dreamhost has a cool backup system for your normal files that you can access from your account, but MySQL is a little different. Ideally--and I'll be doing this from now on--you should back up your own databases at the very least to your home directory on Dreamhost (since that's likely on a server other than your database and will be included in the regular filesystem backups). It's always nice to know that they've got your back though.