Google has begun penalizing sites that sell links on their pages to advertisers, reports Search Engine Land.

According to Danny Sullivan's research, the page ranks of several sites that sell links have dropped dramatically in the past few months. These drops are inconsistent with the natural ebb and flow of the Internet.

Google later confirmed it is penalizing sites that sell links, and may wind up dropping violators from its search engine altogether — an online condemnation to Siberia, considering Google enjoys the majority of search traffic across all major search engines.
Getting linked from a high-profile site has an impact on the perceived popularity of the linked site, making inorganic linking relationships a common, if controversial, tactic for online marketers looking to boost the status of their sites.

A higher PageRank also results in higher placement in organic search results.

Google says all PageRank drops are coming after a manual review. The final process on how to penalize both buyer and seller is not worked out just yet.