tedster - 2:29 am on Jul 16, 2011 (gmt 0)
Yes, the PageRank scale is "stretchy" - but not because of Panda. The mathematical definition of PR insures that the scale stretches because:
1. it always goes from 0 to 10
2. the scale is not linear but roughly logarithmic/exponential
So as the total number of URLs in the index grows, the 0 to 10 PR scale must be something like a rubber sheet, making room for the new URLs and new links. And because the scale is not linear, there is a general tendency to make it harder to get a higher PageRank number - even though as a relative signal of strength a URL compares quite well to others.