hey fordem,
you mention it isn't an advertised feature, based on this link i would say it is advertised, hence where i got my information from ... if you look under simplified management or do a search for backup you will see the following:
SIMPLIFIED MANAGEMENT
The DNS-323 can automatically back up your data regardless of your computer’s operating system (Windows®, Mac®, or Linux®). For Windows users, the included feature-rich backup software can help you create schedules and rules including real-time full or incremental backups and storage quotas for specific users and groups
http://www.dlink.ca/products/?pid=DNS-323