It's not really though, is it? It shows the PR value from only one data center - probably the one data center that hasn't been updated for the past 3 years because some engineer spilt his coffee on the electronics.
www.pagerank-monitor.com is a site that someone told me about.. it's pretty handy this is also a great site http://livepr.raketforskning.com/?u=
might as well self promote www.prmenow.com Has PR checker tool, backlink checker, plus a sweet pagerank button thing you can put on your site, and a few useful articles