Found this while doing some research, is it necessary to submit to search engines anymore?

As of April 11th there is no longer a need to manually submit your sitemap to search engines. Last fall, the major search engines agreed on a sitemaps format. You can now add a simple line to your robots.txt file and let the engines know where your sitemap document resides on your site.

Just include the following line in your robots.txt file and you should be all set:
Sitemap: http://www.yourdomain.com/sitemap.xml

Robots.txt has traditionally been used in a more prohibitive fashion - by telling search engine spiders where not to go on your site. This latest sitemaps implementation of robots.txt however is telling the spiders where TO go.

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