Here at my company we have three Hudson CI servers with 100+ jobs configured. We are looking for an automated way to periodically backup job configurations and
Besides the Backup plugin there is also the thinBackup plugin to backup only the configuration files (available for Hudson or Jenkins)
I personally like to do all system backups via one system that is usually a shell script in the end. I wrote a Jenkins specific script for that (works for Hudson too). See https://bitbucket.org/toomasr/jenkins-stuff/src for more information.