Matt Cutts, a Google engineer who leads their webspam team announced that Google is updating their tool bar Page rank soon.

What is “toolbar Pagerank”?

In the good ole days of SEO Google’s index was periodically updated, and the SEOs all rushed to check out their Pagerank and positions. Back then the correlation between the two was much bigger, and the Pagerank in the toolbar was what a lot of SEO professionals fixated on.

Over time, Google got better at discerning the context of pages and rankings depended a lot less on the url’s general Pagerank and Google also started delaying their tool bar Pagerank while beginning to constantly calculate the ranks. One of the reasons Google does this is to make it harder for SEOs to manipulate their rankings, as the feedback is delayed and it’s harder to tell what worked or didn’t work.

So now Google periodically (every 3-4 months) takes a snapshot of their Pagerank data and pushes it out to the public through the toolbar (and the various other sites that query their toolbar servers). For more information read Matt’s explanation here.