Time to update your robots.txt file to include sitemap.
All the major search engines have announce that they are now supporting Sitemap Autodiscovery. Which boils down to an additional line you will want to add to your robots.txt file.
For Community Server 2.1 with the Google Sitemap Module installed. All I had to do was add this line to the end of my robots.txt file.
Sitemap: http://tlaughlin.pandorasystems.com/GoogleSiteMapIndex.aspx
You need to use a fully qualified domain name, unlike the Allow and Disallow lines in a Robots.txt file.
I add this today. Time will tell. Most of my traffic comes from Google. Maybe now I will see a little more from MSN, Yahoo and Ask. Who have all adopted this standard.