How quickly does Pagerank get updated?

I posted a blog entry on e-consultancy yesterday about Google Analytics. The main page has a Pagerank of 6 at the moment. My entry shows up on that page as a link but the entry itself has a pagerank today of 0.

I'll keep an eye on it to see if and when this changes. I would expect it to as Google crawls the site and makes a note of new content.