Google’s policy on paid links has long been the same: it does not approve of buying or selling links for the purpose of manipulating search engine rankings. Links that use the “nofollow” attribute or some sort of redirect to prevent the passing of PageRank are fine with them.
“Our goal is to provide users the best search experience by presenting equitable and accurate results. We enjoy working with webmasters, and an added benefit of our working together is that when you make better and more accessible content, the internet, as well as our index, improves. This in turn allows us to deliver more relevant search results to users.”
“If, however, a webmaster chooses to buy or sell links for the purpose of manipulating search engine rankings, we reserve the right to protect the quality of our index. Buying or selling links that pass PageRank violates our webmaster guidelines.”
Cutts goes through the history of Google’s stance, and the reasons behind it. Where some webmasters questioned Google’s clarity on the issue, here Cutts makes it abundantly clear that Google is indeed cracking down on buyers and sellers of links that violate its policies.