tedster - 5:37 pm on Oct 26, 2007 (gmt 0)

The PR and the backlink juice that are used for rankings are calculated and updated continually on Google's back end.

This was a major computational advance by Google a few years back, and it made "PR updates" into a non-event, except for those whose business model depends on the toolbar green. Website rankings reflect much more recent PR calculation than what shows on the toolbar.