One site went from PR2 to PR3..> main page and main inner pages are all PR 3 (these pages all have backlinks). My other inner pages with minimal content and no backlinks are all PR4. My about me page (1 paragraph of content) and contact me page (no content at all) are also PR4. Also, rankings for keywords haven't changed at all.
Either PR is constantly updated and incorporated into rankings (with official PR update 3-4 monthly), or PR makes no difference with ranking!
Still was nice to have a bunch of pages with PR4!