While all the webmasters are gasping about why their pagerank is gone and others are contemplating if Google PageRank is dead.

It simply turns out that Google has updated the URL which is used to query it. This has caused various toolbars and websites to stop reporting the Google PageRank number.
 
So it is only a matter for the developers to update the pagerank tools and the PR reporting should once again work accurately.
  
Update
Today, we can count on the fingers of the hand the websites that have changed the query URL and re-display the PageRank properly. Here is a guide on how to update the Google PageRank for SeoQuake for Firefox:
Google PageRank Update Fix [Tips & Tricks]
 
And if you are not using Firefox SeoQuake to check your Google PageRank you can use our online Google PageRank tool @: Check Your Google Page Rank Here – Updated To Use The New Google PageRank Query URL which is updated to use the correct query URL.
 

Google PageRank URL Change
> The old URL Google PageRank syntax was:
http://toolbarqueries.google.com/search?client=navclient-auto&features=Rank&ch=8f3b58e04&q=info:[ URL ]
 
> The new Google PageRank syntax is:
http://toolbarqueries.google.com/tbr?client=navclient-auto&features=Rank&ch=8f3b58e04&q=info:[ URL ]