Google Page Rank

Following up on last weeks discussion on Google's toolbar PageRank. This blog continues to have a Page Rank of 5. That seems consistent with what I've been hearing; the inbound links haven't changed, I don't sell links, or have a massive network of links (blogroll expansion to the left, notwithstanding).
However, I have recently purchased a number of other domains through SEODomains.org They've all seen dramatic PR drops, from PR4 to PR0, and a couple from PR3 to PR1. Now for the $9 registration, I had figured I'd just put up a basic blog page, and see if there was any traffic. I'm assuming the PR drop is more from the lack of content on the pages for a while, rather than anything else.
One other interesting thought; posts 10/2 and back have Page Rank show up in the Google Toolbar, those after that, don't.