bhartzer - 7:14 pm on Mar 15, 2004 (gmt 0)

I think the key here is "only update the visible PR and link: data". I would assume that they would update PR and link data more often but only update it so we can see it once a Quarter.

It's actually not for all the sites, though. I have noticed that Google has been updating PR for certain sites (domains that are going to expire soon are being given a PR0 shortly before they expire).