CainIV - 3:07 am on Feb 28, 2011 (gmt 0)

What's interesting to me is timing.

What made this update important now? Was it improvement in the detection of low-quality content from Google?

If so, how can Google even begin, at an advanced level to detect "low quality"

And what does this say about the fact that many of the websites in fact ranked for years. Was Google simply showing 'low quality' SERPs that that time for those particular queries? What made Google determine that those same content pieces were now low quality to the user?