BigDave - 4:35 pm on May 12, 2008 (gmt 0)

Creating the sitemap only tells Google about the pages, it does not guarantee that they will be crawled. You need incoming links, and pagerank for Google to crawl your entire site. While every single one of those pages will have its own pagerank (only if it is crawled) it will be an incredibly minute amount. It is incoming links that make the real difference.

While you may get an initial burst of activity indexing a small portion of your site after submitting your sitemap, I would say that a general rule for young sites is that Googlebot will follow any incoming link to your site three clicks deep. I'm talking real incoming links, not comment or guestbook spam.

What is most likely to happen is that your site will get flagged by Google as probable garbage, given a lack of incoming deep links to those 3 million pages. Then you will just be left with whatever Yahoo and MSN send your way.