Google pushes out toolbar PageRank updates every 3 months or so. The most recent one was over the weekend, which helped generate some buzz. But the reality is, what Google shows as PageRank in the toolbar is way out of date. How do we know?
The Google Blog wrote Friday, We knew the web was big..., which talks about how big the web is. Google said they have "processed" 1 trillion unique URLs on the web. Right, Google did not say they have indexed 1 trillion pages, but they have "found even more than 1 trillion individual links." The number of web pages or documents they lead to, is unknown - to Google at least. Google said, they "don't have time to look at them all," to figure that out.
But what is extremely interesting is that Google says they reprocess "the entire web-link graph several times per day." That means Google will recalculate and process those links, about a trillion of them, not just once per day - but several times per day. Can we infer from that, that Google will reprocess the true PageRank of a web page several times per day based on that linkage data? Maybe.