While Google continually works on shifting the ranks of pages around, it is well known that around every 90 to 120 days, Google completely updates PageRanks, thus doing its little dance, and leaving people with a variety of different rankings. Sometimes people increase in PageRank, and other times people fall. There are also a few that stay in the same spot, and thus wonder why everyone is making a big deal.
That time is nearly at hand, with one set to happen sometime this August, and while it is most likely too late to do anything that would effect your PageRank in a major way, you can already start preparing for the next update.
I have already written a short primer on what can effect your PageRank, but to summarize it all into one bit of information: get links, give links, don’t sell links and of course write good content.
Good luck to everyone in the upcoming update.