There seems to be some confusion surrounding XML sitemap usage so I'd like to clear that up.
Many people question the need for an XML Sitemap, and for frequently updating it.However, creating and submitting an accurate up-to-date and properly formatted XML Sitemap in a fundamental part on good on-site SEO and really pays off.Websites are never hurt or penalized in any way by using sitemaps. Even if you already have a XML sitemap, adding a second will still help. In fact, if you look at Google's own robots.txt file ( http://www.google.com/robots.txt ) you can clearly see they are using multiple sitemaps themselves.
Google recommends XML Sitemap submission in all of their Webmaster and SEO tutorials: " Whether your site is old or new, we highly recommend you submit an XML Sitemap" - Google Webmaster Tutorial
In fact, recommending people NOT use a XML Sitemap in #4 on SEOmoz's list: "The Biggest SEO Mistakes SEOmoz Has Ever Made" written by a widely recognized SEO expert, the CEO of SEOMoz himself: http://www.seomoz.org/blog/whiteboard-friday-the-biggest-seo-mistakes-seomoz-has-ever-made
Attracta is the largest supplier of XML sitemaps with over 2.8 million websites using them, and that seems to be what makes them have such a very high PR. Also, Attracta sitemaps are free, show you exactly when Google and other search engines access them, and can be updated and resubmitted at anytime.
