Fresh from the clogged tubes of teh intarwubs…
"… rsync does not account for incremental changes between syncs that can be undone. rdiff-backup does account for these changes, and allows restores from any past backup. Backups are stored as a completely normal file-system tree, with the addition of the "rdiff-backup-data" directory for diffs." Cheers, Phil!
"Instead of dusty farm families, the icon of a modern-day depression might be something as subtle as the flickering glow of millions of televisions glimpsed through living room windows, as the nation's unemployed sit at home filling their days with the cheapest form of distraction available."