To give a little history, PageRank used to be a major indicator in determining where your website (web page) ranked in the search engines. PageRank ranges from 0 to 10, 10 being the best.

The higher the PR (PageRank) the better you ranked (historically) for that particular page (each page is assigned its own PageRank).

PageRank was important before other behavioral factors/indicators took the limelight. Google and other search engines used PageRank as an indication of popularity among web searchers (almost like a meta-behavioral indicator). Now Google (and others) have been tracking real behavior, like click behavior, search history, geographic location, etc. Its a web users actions that will determine a web page's "popularity" and relevancy, which in turn has helped to make PageRank (mostly) obsolete.

Has Google dumped PageRank completely? No. They haven't said that officially. They have officially said that following PageRank as the sole indicator of ranking and indexing of your website is foolish and incorrect. Much like putting all your time and effort into ONLY optimizing your meta keywords on each page.

Google has always said that there are 200 indicators that they look at for each page when determining ranking and indexing. PageRank is still one of those indicators (as is meta keywords). You need to monitor as many of these factors as you can to keep a good mark on why your web pages rank the way they do.

As Google says, a high PageRank might not mean that you rank well for a certain term, but a low PageRank can be an indicator of why you DON'T rank for a certain term.

Read more at "Google Ditches PageRank in Webmaster Tools"