Slashdot has a discussion on Google and backup. The question:

I am doing almost all of my computing in the cloud. Google Reader, Calender, Email, Docs and Notes have become my tools of choice … is there a one-touch solution that will take all my data from the various online apps and archive it on my home server?

The answer appears to be “No” – that is, there are ways of doing this with scripts, offline email clients and so on, but there is no one-touch solution.

It strikes me as a valid concern. It is not just a matter of trusting Google not to zap your data accidentally – though Google accounts have been known to disappear. Another scenario is that someone guesses your password, or grabs it via keystroke capture, and deletes stuff on your behalf. It just isn’t sensible to have only one copy of data that matters to you.

Arguably this is one advantage of synchronization services like Live Mesh, but these have a flaw too. Synchronization will happily copy a corrupt document over all your good copies. That’s why I like version control systems – they keep a history.

Even in the admin features of the premier edition, aimed at businesses, I don’t see backup covered.

It can’t be that hard to fix this with something like, say, differential backups from Google to Amazon S3. It would be unlucky to fall out with both companies simultaneously.