AlyssaS - 1:09 am on Feb 25, 2011 (gmt 0)
I own two long tail sites where I have removed all adsense ads a few weeks ago and these site do not show a drop.
There is a big clue in the quote above from SEOPTI
The only pages where I have seen a drop have had links from Ezine articles - the drops on those are about 20 points, I am assuming that the ezines lost value which caused my pages to drop.
People, I think this is the infamous "content farm" algo change that we've been expecting, where large sites with a varied articles on many subjects, monetised with Adsense, are being devalued. And if those sites link to you, you experience a hit as the link is devalued.