According to PR Weaver, Google has once again changed the checksum for determining a site's PR. This could explain why some of the tools I have been testing for others lately have been mis-reporting PR. I certainly don't have the skills to crack the new checksum, but I am sure that others will do so in record time.
What puzzles me is why Google even bothers. Surely they know that the code will be cracked, probably within a day or two of the change, so why expend the manpower to do it at all? Ah well, I have to say that I don't understand much of what Google is doing these days. So, why should I understand this one small thing?