Mind you, it also pertains to iDevices (which should come as no big surprise).
In How to back up your iPhone and iPad before an upgrade, Chris Gonzales gets into a lot of gory details, including security and restoring from your backups.
The best part of the article is a quote from Merlin Mann: ‘If you don’t have time to do backups, you so don’t have time to upgrade.’ Bring on the dragons!