PR is given and transfered all the time. But you only see the PR in your toolbar updated four times a year (snapshot)
But if page A is 301'ed to page B, then will the toolbar also show a PR on page B. Or is it just internal PR transfer?
What about regain the PR from the "Page A" ? I have some domains that I used 301 and passed the PR to a domain B, now I want to use the domain A again but www.validrank.com reports the domain with fake PR. I must wait to the next PR update to regain PR?