It is observed since a week ago that there is a consistancy in Rank for Competitive Keywords on SERPs from different Data Centres. This must be the first time after a long contradiction over the Ranks on different DCs.
I had seen that there is a difference in the ranks in different Data Centers couple of weeks ago. Aparrently, I observed that my site that was ranking at 3rd started ranking 2nd during five days ago on all the Data Centers and yesterday when I observed the Data Centers for the same keyword my site started ranking 3 again consistently on all the Data Centers which was not the same before. It is the Bigdaddy that evolved from Pubcon in Jan'2006. Mattcutts described it in his blog's Q&A as the two data centers: 66.249.93.104 and 64.233.179.104.
