tedster - 6:59 pm on Mar 4, 2011 (gmt 0)
Looking at analytics for about 50 quality domains that took an initial drop, I see a lot of step-wise recovery. The Google traffic graphs all look bowl shaped, but with one side steep and the other side sloped more gradually. The recovery in some cases is back to previous traffic levels as of Thursday (yesterday) - but not in all.
None of these recovering sites took any steps to make improvements happen, so I can only assume that there is some form of algorithm adjustment happening. It may be automated machine learning, or it may be newly introduced changes - clearly, that's hard to determine. But seeing an incremental improvement one day after the next, makes me lean toward automated machine learning, with "layer 2" of the algorithm yet to come.