Google has changed the way it processes the nofollow attribute. These changes have an impact on how you can use the nofollow attribute for PageRank sculpting on your website.
What is PageRank sculpting?
PageRank sculpting is the attempt to control the link power of one website page to another page of the same website. For example, when Google finds a website with three links then the link power is evenly passed to all three links:
Links that are marked with the nofollow attribute shouldn't be followed by Google. That meant that the other links on the web page benefited more from the high PageRank of the page. It worked like that:
In this example, link 1 passes no link power while link 2 and 3 each pass half of the available link power to the target page. The result is that the linked pages have a higher chance of getting listed in the search results.
What has changed?
Google's Matt Cutts recently made a statement about the way Google now treats nofollow links:
Link 1 still doesn't pass any link power but the link power of that link is simply discarded.
What does this mean for your website?
The change means that PageRank sculpting with the nofollow attribute does not work anymore and that it now makes sense to remove any nofollow links that go to your own website. You're just wasting link power by using the attribute for links to your own pages.
Do not waste your time by trying to manipulate the links on your web pages. Better concentrate on a good user experience with good web page content and an easy to understand website navigation. Websites with a good user experience usually get more links from other websites.