Is there any feature that will generate a google friendly sitemap - as per this site?

http://www.xml-sitemaps.com/

We have built a handler in an existing asp.net application (eg. sitemap.axd requests) - that looks at our .net web.sitemap file to generate the appropriate xml file. Would we have to build something from scratch - and is it easy enough to access the list of pages programatically (unless something already exists).