PR is very outdated and lately it is causing lot of issues to Google: link sales, PR maniacs and so on.
A sudden removal of PR will cause some panic and issues to many applications and sites that use PR queries for various tasks.
So Google is probably removing PR gradually. They don’t update for a very long period, so webmasters learn how to live without it.

There are more than 7 months since the last update.
Usually Pagerank was updating every 3 months.
Is Google doing some major changes with the Page Rank?

As you probably know, Pagerank is based upon this formula:

L() returns the number of outgoing links. Example:
L(www.google.com)=28
L(www.yahoo.com)=164
Assuming google.com and yahoo.com has the same PR and the same backlinks, it’s much more valuable to get a link on google, because of the low number of outgoing links.
Therefore, we need some tools to count outbound automatically and here are some: