I only found this info link
http://searchengineland.com/080430-081837.php
Seems the toolbar is updating. Don't know if it's done yet.
I created a bunch of new hub sites last month, so far I see
PR4: 1
PR3: 1
PR2: 18
PR1: 4
One of the PR1s has literaly almost 100x the SE traffic the PR4 gets.