We're backup fanatics and have saved many a web designer's *ahem* ass by retreiving files that they assumed were long gone.
Your site's files and databases, VPSs, and email are all backed up every night to servers inside our datacenter and then a copy of those backups is sent to another datacenter for off-site storage.
We retain backups incrementally every night for 7 days, then again on the 1st of each month for three months.
So if you need a version of a file from your web site from, say, four days ago or two months ago, just ask and we'll grab it for you!
That said, backups are can become corrupt, backup servers can die, and things can just go wrong, so we highly recommend that you backup your data as well!