sitemap or ror how important? its important really this what search engine looks for to index your page for site... which are files in xml format wihch gives idea about content of your site... now google have a option that you can submit your sitemaop.xml file personaly also ... for us meta tag + sitemap both are important.. shiva webmaster..
Google's meta tag thingy is a way for you to look at your site stats... to verify that you own the site that you are asking to see stats about. It has nothing to do with being indexed (if this is what you meant). RoR is an up-and-comer that looks quite promising... kind of an OPML meets GoogleXML Don't forget the original HTML version that ALL spiders can use to crawl your site (yes, including Google).
A Website without Google sitemap can also Perform much better and google will have to improve their sitemap program a lot.