Is the panda update going to affect PR calculation? Is PR going to play a weaker role in search ranking?
This sums it up perfectly; the Panda update didn't have any affect on Pagerank values directly. I would imagine that some content farms lost a lot of their inbound links and may have a cascading effect on their Pagerank value. But at the end of the day the Pagerank number we can see is simply a snapshot of the past.
I suppose there is some relation between Panda updates and PR changes. My 4 sites were penaltized by Panda and their PRs were decreased from 3-4 to 0-1.
There is no corloration between PR and Panda as far as I can tell. I know of a strong PR5 website that has been a PR5 for 2+ years and is hit with the Panda bug.