indyank - 6:00 am on May 19, 2011 (gmt 0)
March and Early April "different sets of pages" have finally settled down to?
Those pages appeared on the front page post panda and they have disappeared now.I am also seeing a few pages (not all) that they replaced making a comeback to page 1. The other pages that remained intact from pre-panda continue to remain in the mix and these are from big domains like wikipedia, etc.
When it comes to throttling, it is probably accomplished by having different result sets on their various data centers.For example, even within the same country, what you see in sydney may not be seen in Melbourne and so on.