That somewhat depends on what you mean by partial. You can not run the
backup util for anything but the complete sharepoint server. There are a
few 3rd party tools see http://www.sharepointserver.com/backup.html but
at this time I do not believe that any backup  solution provides support
for single workspace backups yet.

There is also the SPSIMEX util from the resource kit. It is not so much
a backup as it is an import/export util. You will not get everything
that the backup will such as discussions but you can export a workspace.
If your ws is large, this can take some time compared to the backup
tool. Each document and it's versions are copied to the file system.

Hopes this helps. I am sure that others will let us both know  if a
single ws backup tool has come available.