I've noticed over the past few weeks that several of my (I believe) Panda/Penguin affected sites seem to receive a massive rush of traffic during a given hour in the early morning (GMT).
This doesn't occur daily by any means but it's in marked contrast to the traffic patterns either side of that hour. Typically during that one hour period the traffic volume will be 6-8 times that of any other hour that day.
Does any one know or care to speculate about the cause?. Any similar experiences?