ortelius - 10:29 pm on Feb 27, 2011 (gmt 0)
I'm pretty sure the new algo has a heavy weighting for identifying similar content, which the algo takes as the antithesis of original, unique content. That gets the scrapers but it also can get quite a few well-intentioned innocents.
I have no better ideas than any others on here (if that) -- - but I want to point out that the post by Whoa is, in many ways, (not all) a description of my site, which dropped the typical 40 - 50% traffic on Thursday.
My content is all original, it's well-researched, but, since 85% of the pages on my site are database driven "entries" almost like a dictionary, it's quite possible that the overall look, to a machine, is one of a bunch of "similar" pages. I don't think that's the whole story, but I think Whoa's comments ring very true to me. They point in the right direction, I think. (Or at least one of the right directions!).