Google describes PageRank (PR) as
“PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page’s value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages ‘important’.”
Webmasters just dream about getting PageRank 10. Though it is unofficially proved that PageRank has very little effect on SERP, webmasters would do anything to achieve higher PR. There are webmasters or SEO companies who don’t even slightly hesitate to apply Black Hat SEO / spamming for PR even though know they might be blacklisted in Google.

Anyway, here is a list of PageRank 10 websites according to Google PageRank update on April, 2008.

Title	PR	Google Banklinks	Yahoo! Backlinks	URL:
Adobe	10	82,600	2,869,228	http://www.adobe.com/
World Wide Web Consortium	10	166,000	2,778,033	http://www.w3.org/
Macromedia	10	31,600	738,824	http://www.macromedia.com
U.S Department of Energy	10	43,000	1,832,883	http://www.energy.gov
National Aeronautics and Space Administration	10	64,400	1,638,342	http://www.nasa.gov
Google Search	10	3,830,000	264,426,369	http://www.google.com
National Science Foundation	10	27,100	1,512,528	http://www.nsf.gov
The White House	10	67,800	1,765,906	http://www.whitehouse.gov
Real Media	10	130,000	1,789,753	http://www.real.com
US Goverment website	10	142,000	32,776	http://www.usa.gov/index.shtml