Google continues to crack down on those text link advertising methods which don’t carry the “nofollow” attribute as a “machine-readable disclosure.” The latest move, triggered by communication between Google’s web spam team and the Google AdWords department, as Google’s Matt Cutts says, is to disallow the advertising for such PageRank-selling schemes via Google. Compare the ads for the query pr8 – i.e. “PageRank 8” – from November 18th with today.
Fair or not from an outside perspective – see some previous background – this change in implementation is in accordance with Google’s existing AdWords and Webmaster guidelines. The AdWords guidelines stated “Advertising is not permitted for the promotion of ... search engine spamming,” pointing to the webmaster guidelines for further definitions of unacceptable techniques... and the webmaster state “Buying or selling links that pass PageRank is in violation of Google’s webmaster guidelines.”
While many to most paid links marketplaces are now disappearing from ads in Google search results and sites using AdSense, there is nothing in Google’s guidelines that would disallow one to build a “nofollowed” paid links service, as this ban is only for what Google considers “PageRank-passing” ads.