Google has always been against paid links and the idea of selling Page Rank. Recently they have become more aggressive in lowering the Page Rank of sites that sell paid links.

Take for example Text Link Ads. This service, which matches link sellers with link buyers, has been removed from the Google search indexes. The only way for them to get included in Google's search results is by buying ads via Google AdWords.

One of the biggest "Make Money Online" blogs, Johnchow.com has seen his Page Rank drop from a six to a four over the last few weeks. John has had other problems with Google in the past. Earlier in the year he ran a "review me for a link" program that he used to Google Bomb himself to the top of the "Make Money Online" search result. Afterwards Google dropped him from their index. If you do a search for "John Chow" you will not see his website.

In a recent article on Search Engine Land Danny Sullivan pointed out some of the extreme cases of Google penalizing a site for selling links. The most prominent example is the Stanford Daily News that went from a PR9 to a PR7.

Because Page Rank is owned by Google it is completely up to them how they assign it to websites. However, by making the existence of Page Rank public and telling webmasters how it works they create a situation where people will want to use that system to increase the traffic to their sites or the income from their sites. Google could very quickly kill the incentive to sell paid links to pass on Page Rank simply by making Page Rank an internal only metric. If no one knows what their Page Rank is no one will be able to game the system or sell paid links based on it.

Google is completely within its rights to penalize the Page Rank of any site it chooses for any reason it chooses, however, removing a site from the search index is not a good idea. If I am searching for something specific (text link ads) and the site does not come up on top I am going to suspect a problem with Google's ability to search the web and deliver to me relevant results. If Google were a search company they would care about this. Sadly, Google is not a search company, they are an advertising company that tells people it is a search company.

Keep your eyes open if you follow SEO and Page Rank, some of my sites have just been hit with Page Rank updates and the ones that sold Paid Links all suffered.

Data is checked via UrlTrends and Smart PageRank

For further reading I suggest you go to Andy Beard's blog and Daily Blog Google Tips

Update
A reader emailed me to suggest that part of the Google Page Rank change may be attributed to Netscape Propeller. When they did the move several weeks ago they went from a PR 9 site to a PR 0 site. All links coming from Netscape have now been adjusted to be worth 0PR. How many of the sites suffering now were high profile on the old Netscape?