In an email to Search Engine Journal editors, Matt Cutts said, “The partial update to visible PageRank that went out a few days ago was primarily regarding PageRank selling and the forward links of sites. So paid links that pass PageRank would affect our opinion of a site. Going forward, I expect that Google will be looking at additional sites that appear to be buying or selling PageRank.”

Sites affected by this update included Forbes, the Washington Post, Search Engine Roundtable and Search Engine Journal, all of whose PR fell to 4, SF Gate and Sun Times whose PR has fallen to 5 and TechCrunch and Engadget whose PR was reported to have fallen to 5 but is now back to 7.

Changes in the PageRank do not seem to have affected traffic to any of these sites though. This may change over time if Google decides to punish the sites for selling links. However, for now it seems that the PageRank update was only meant to remove their ability to sell high PR links by simply dropping that number.