Link sculpting comes from the idea that a Google spider will not follow every link on every page. Depending on the length of a web page and the number of links it contains, the Google spider will 'get bored' after a certain point and stop following the links.

The link sculpting idea involves placing a 'no-follow' on all but the most important links on a given page.

This way you are encouraging the spider to concentrate on your most valued pages and so increase the amount of authority, page rank or indexibility for those pages.

Unfortunately Google doesn't like the idea of websites controlling the value of their own links.

The outcome is that many SEO companies are expecting Google to start analysing the way websites are using 'no-follows.' Their technology can easily see what percentage of links on each page are 'no-follows' The question is, where will they draw the line between fair use and deliberate manipulation.

Recent turmoil in Google rankings seem to be associated with 'no-follow' links, but we will have to wait and see what Google's purpose is and how they are going to use this data to improve the search results for end users.