If you`re interested in SEO, then you should subscribe to www.sitepronews.com newsletter. They always have good articles (dunno if they are original or “private label articles”).
Latest article by Eric Lester is about exploiting in google`s algorithm and how one guy filled Googles index with few billion sp@m pages. He explains that Google indexes each subdomain as independent, so on one domain you could generate countless pages with keywords and AdSense ads. In some previous article they stated, that subdomains add PR to the original domain, so this is even more useful for those who practice “artificial SEO”.
Anyway, i`m sure you have seen a page that contains nothing but keyword stuffed content with ads all over the page, and lately these spam pages get more and more top positions in SERP`s. IMHO search engine sp@m will get more annoying than email sp@m in the near future, so be ready. Right now google is trying to fix this loophole and removing fake pages manually by searching them using the spammer`s original domain with “site:”, but meanwhile copycats are out there writing theyr generator scripts.
Read full article here (printable, readable version) or full site article.