I am all for saving time. In the old days backing up a WordPress blog meant either using phpAdmin to back up the database or manually logging into each blog and using a backup plug-in.
No more.
Starting with WordPress 2.0 the bundled backup program was taken out and made a separate plug-in. Version 2.0 of the WordPress database backup plug-in takes advantage of WordPress cron program and will email a backup on a regular basis. I use once a week, though the granularity can be once an hour.
Once installed, go into Manage then Backup. On the bottom of the page the time frequency of the backup and the email address is set. Note if you choose once a week, the weekly backups are on the day you hit submit. Since I like getting backups on Saturday I started all my backups on a Saturday.
Note this only backs up the WordPress database; not the WordPress source code.
admin Doug