The new attribute is called "nofollow" with rel="nofollow" being the format inserted within an anchor tag.

This is how the link would look after the nofollow attribute has been added, with the attribute portion shown in bold:
<a href="http://www.site.com/page.html" rel="nofollow">Visit My Page</a>

If Google, Yahoo or MSN see nofollow as part of a link, they will:

1. NOT follow through to that page.
2. NOT count the link in calculating PageRank link popularity scores.
3. NOT count the anchor text in determining what terms the page being linked to is relevant for.

Read more about nofollow attribute here