SilverStripe Google Sitemap Auto Update
This module simply passes the responsibility of physically generating a
to the QueuedJobs Module which it
does after each write.
The advantage of handing off this procedure to a message queue rather than just doing it immediately, will likely be more apparent on busy, content-heavy sites, who's content authors may already experience time-lags when saving content in the CMS.
If you need anything more complicated such as auto-alerting Google of changes to your sitemap, you might consider the standard Google SiteMaps Module.