There are numberless complaints in the forums that the Google PageRank went missing in action and is no longer working.
The issue is not with Toolbar PageRank. Google appears to have disabled
the display of PageRank on browser toolbars and online ranking checkers.
It is causd by Google's lookup URL for the Pagerank. Toolbar plugins,
such as SEOQuake and SEOBook, which had been displaying the Google
PageRank for the site being viewed are now showing as either N/A or 0.