Documentation for module http://drupal.org/project/domain_xmlsitemap .
This module helps you adding a different sitemap for every domain configured via Domain Access.

(Placeholder project for the contrib module to integrate the XML sitemap and Domain Access modules together.)

Dependencies

After enabling the domain_xmlsitemap-module i can add new sitemaps here:
admin/config/search/xmlsitemap -> 'Add new XML sitemap'
On the following page there is the option to select a domain-entry.

After admin/config/search/xmlsitemap -> check the new domain entry -> 'Update cached files'
i found a sitemap.xml for the domain-entry.