On the Why should I report paid links to Google? page, Google changed the document to add the words “selling links” through the page. One line now reads:
Buying or selling links that pass PageRank is in violation of Google’s webmaster guidelines and can negatively impact a site’s ranking in search results.
What does Google recommend you do if you sell ads on your site?
(1) Adding a rel=”nofollow” attribute to the anchor tag
(2) Redirecting the links to an intermediate page that is blocked from search engines with a robots.txt file
Postscript From Danny: I’d previously recommended that Google update their help pages to reflect PageRank penalties might now happen. Neither of the two key pages I’d highlighted were updated as part of this round of changes.