Watch this video interview with Sean Daniel (Microsoft PM for SBS) where he discusses the Small Business Server 2008 backup wizard and shares other information pertaining to SBS 2008 showing off parts of the SBS 2008 console.
The backup wizard sports many improvements in SBS 2008. Now backing up to external storage drives only, you can use multiple backup storage drives and rotate onsite and offsite without any confusion. Beware that these will have to be dedicated drives as they are formated by the backup wizard. SBS will perform a full backup the first time a drive is used and follow with incremental backups thereafter. If you swap the drives, SBS will identify the drive (recognizing the drive hardware so the drive letter doesn't matter and can change), and be aware of what was last backed up to the particular drive and run the incremental backup from that point in time. This way you will always have a full backup on each external drive. And despite what you may have heard about Windows Server 2008 backup and Exchange Server 2007 APIs, the backup in SBS2008 will include backing up Exchange.
Watch Seans interview here SBS 2008 PM Interview and Demo