Attention Please "Google Changing the PageRank Algorithm"

If things keep at this pace I might rename this blog to Daily Google Tips. Over the last two weeks we have been talking about Google every other day. This time it is the PageRank buzz again.
Both Problogger and Copyblogger, two of the most popular blogs on the niche, announced that their PR dropped from 6 to 4. Previously other authority blogs confirmed that they lost PR, but the suspect was towards paid links. Given that Problogger and Copyblogger are not selling links, it might be just a readjustment on the PR scale.
Some people are arguing that since the PR drop is not generalized, it must be a slap from Google due to practices that conflict with its guidelines. Andy Beard suggested that the sites that got penalized were either selling links or exchanging them inside large blog networks. This is a feasible explanation given that most of the Weblogs, Inc blogs (Engadget above all) were penalized, and they do not sell paid links either.
Here is a list that I gathered with big blogs that supposedly lost PR on this issue:

• Statcounter (from 10 to 6)
• Engadget (from 7 to 5)
• AutoBlog (from 6 to 4)
• Problogger (from 6 to 4)
• Copyblogger (from 6 to 4)
• AdesBlog (from 7 to 5)
• Search Engine Journal (from 7 to 4)
• Quick Online Tips (from 6 to 3)
• Search Engine Roundtable (from 7 to 4)
• Blog Herald (from 6 to 4)
• Weblog Tools Collection (from 6 to 4)
• JohnTP (from 6 to 4)
• Coolest Gadgets (from 5 to 3)
• CyberNet News (from 6 to 4)

Update: It looks like mainstream websites that were selling links were also penalized:

• Washington Post (from 7 to 5)
• Washington Times (from 6 to 4)
• Charlotte Observer (from 6 to 4)
• Forbes.com (from 7 to 5)
• SFGate.com (from 7 to 5)
• Sun Times (from 7 to 5)
• New Scientist (from 7 to 5)
• Seattle Times (from 6 to 4)