Tallon - 12:40 pm on Mar 12, 2011 (gmt 0)
I heard second-hand today from a representative for a major ad network that a number of his clients who have long-standing sites with original content that were initially hit are experiencing a rebound. I suspect that Google is either refining its test for what site should get credit for initiating content or partially rolled back the changes to that algorithm.
I experienced slight dips in traffic yesterday on two sites (one large, one small), both experienced slight growth since the new algo. So methinks there was an adjustment somewhere.