chrism - 11:02 am on Nov 16, 2011 (gmt 0)
And as I say that, bang on 11.00AM GMT back to set B.
It's not just my site either, I didn't make that clear. The whole of the first 20 results seem to shuffle, with only one site in the entire top twenty disappearing, replaced by one from page 3.
Of course, this may be a result of hitting different data centres too!