For anyone that hasn't seen it, I highly recommend a project called Clonezilla for system backup. Clonezilla is useful right before an upgrade because it can capture the entire state of a hard drive (think dd, but easier to use) and possibly restore it at a later date. Obviously with this kind of "image" backup, you can't cherry-pick files to restore from it--it's either all or nothing, but the option is particularly good right before upgrades to give you a point to return to if the upgrade fails.
I recommend using Clonezilla in configurations where you have a separate /home folder that's backed up using your normal user-space backup program, and then periodically using Clonezilla to clone your bootable partitions.
Hopefully that helps some folks out.