Google has been updating PR regularly on quarterly basis. Google last Page-rank update in 2013 was on
February 04, 2013. If the Google PR update trend goes in the same way, then
Google Page-rank update will be in first or second week of May 2013.
Webmasters have worked lot to improve search engine rankings and top search engine placement. They are eagerly waiting for next Google Page-rank update in May 2013.