Looks like Google decided to update the visible PageRank on the Google toolbar between the 30th of April and the 1st of May. Well, at least it came after much speculation (on Digitalpoint anyway) of PageRank updates following a string of PageRank penalties across sites that were caught selling paid links.
Overall, most sites received an increase in PageRank, while others had the same PageRank, which is good news for most sites on the whole. Of course, it is bad news for guilty site owners who have sold paid links, since Google is being extremely vigilant (and smarter) on what links are considered paid. Penalties are also carried out during the update, but most of it a few days before the PageRank update. This is done so presumably so that you can address the issue, and request for reconsideration, and have the right PageRank in time for the incoming update.
