If you run your Mac with Snow Leopard (10.6.0 or 10.6.1) be sure to deactivate the guest account. If you try to login as guest by accident or intentionally, you may lose your entire home directory – that happened to me a few hours ago.

http://reviews.cnet.com/8301-13727_7-10346974-263.html

http://www.progtalk.com/viewarticle.aspx?articleid=796

Your Mac is not only affected if you upgraded to Snow Leopard, but also if you set up a new and clean system with Snow Leopard.

So: make sure that you guest account is deactivated and you have a backup of your entire system, especially of your home directory.

It is such a cool documentary. Must see!