Google accepts RSS (Real Simple Syndication) 2.0 and Atom 1.0 feeds. If you have a blog with an RSS or Atom feed, you submit the feed's URL as a Sitemap. Most blog software creates your feed for you. If your site doesn't have a feed, you can use Feedburner to create and publish one. Note that the feed may only provide information on recent URLs.
Note: If you use Blogger to create and publish your blog, Blogger automatically submits a Sitemap for you.