I love reading the countless threads about people thinking they know Google is doing a "PR update in late July". Seriously thoguh, why do people feel like Google does this? Has this ever been proven, even once? Why wouldn't you think G does this daily? There has never been a point where I've seen the posts about a massive PR update and had any of my sites move. Yet at times (randomly) my sites will update and change.
maybe because of posts like this by Matt Cutts ? http://www.mattcutts.com/blog/last-toolbar-pagerank-update-of-2008/ Although it's only visible tool bar PR that updates about every 3 months or so.
http://www.mattcutts.com/blog/whats-an-update/ Google updates continuously and continually within their own database, but users don't see the results until they update the index every 3 months.
Its the way the algorithm works. You can't get the PR of every page instantly. You have to do a lot of recursions which take an awful lot of time. Especially on a data set as big as Google's. Thousands of them. So there may be 2 ways of doing it. Do it on a large cluster that takes a snapshot of the web and then calculates the PR. OR Calculate the PR on the fly. This is much more difficult and I seriously doubt its done. When people see crazy serps up and down, what they are seeing (I believe) is the roll out of new PR scores onto one cluster set at a time. While some of it is speculation I do know that the recursion takes a long time and take hundreads of iterations to get a meaningful results. Also as the value of the whole internet graph is 1, you are looking at doing math with 9 decimal places or more.... Pierce
People readily believe what they are able to see with their naked eyes.... Since regular updates are not made public, the cumulative results whenever made visible, becomes the major/massive update...for the general people. Regards, RightMan
My opinion is that the thing that Google truly excels at is marketing. With PageRank they are using the oldest tactic in the world and playing hard to get. It keeps a good section of the population (webmasters mostly) obsessed with the green bar, and this obsession rubs off to a degree on the rest of the population. As a result of the obsession, more people talk about Google and that only helps to make the Google brand stronger.
Massive PR updates or not - fact is that Google's PR is updated every 3 to 4 months and the only way to see it for yourself is when checking the PR of your sites regularly. PR is only important for sites selling links however as the price per link increases with the PR and some are saying that due to their PR they get more traffic as their position in the SE's are fairly high too.