Google Alters Search Algorithms, Blog Link Farms Targeted

A major Google page rank update has punished large scale blog link farms and similar sites indulging in heavy cross linking by dramatically cutting their Google page rank scores. There is some suggestion that the changes may be related to the sale of text link ads, but at this stage this is not backed by evidence, and a range of sites I checked that are selling text link ads were showing no change in page rank. The only clear change appears to be among large scale blog networks and similar link farms, where each site in the network provides hundreds of outgoing links on each page of the blog to other blogs in the network, in some cases creating tens, even hundred of thousands of cross links. Previously such behavior has been rewarded by Google with high page rank, although it would now appear that this loop hole may now be shut.
http://www.techcrunch.com/2007/10/24/google-declares-jihad-on-blog-link-farms/

http://www.dailyblogtips.com/google-changing-the-pagerank-algorithm/