Google’s Page Rank provides the basis for all of Google’s web search tools. Very often people are noticing that their PR is fluctuating. Sometimes it is growing, while sometimes it is dropping. There have been many cases of famous blogs like, for example, ProBlogger.net having their Page Rank reduced but later increased again. Those can be quite sudden and drastic changes. There are also some bloggers reporting that some of their sites have a high PR even though they only have a few backlinks. It is hard to say what algorithm Google is really using for their calculations, and whether it is reasonable.
Of course, many people say that PR is not that important and one should not focus his attention on it, but on the other hand blogs with high PR might be more respected in the blogosphere. That is because most people care about Google’s opinion.