No whole-system backups. Offsite (across the country) replicated MySQL database with daily full snapshots and periodic encrypted dumps to S3. Real-time encrypted mogilefs backups to S3 on a per-file basis. S3 MFA + versioning is a huge win in both cases. rsync for a small number of exceptions: IMAP data, development trees, etc. When a server fails, just re-image it, bootstrap with puppet, start it back up.
