Splugged - 8:11 pm on Jan 8, 2013 (gmt 0)
If someone can remember my past observation about this strange "effect", I'm having today "hourly rushes".
As for now (from 08:00 PM to 09:00 PM local time) I have a typical "pre-penguin" traffic (1 hit per minute) from G.
Before (from 07:00 to 08:00 PM) I had few visits from G.
I will check in two days my GWT to see impressions stats...