Digg announced today that it has tweaked its policy on the nofollow attribute on external links.

Weve made a few changes to the way Digg links to external sites that may impact some folks in the SEO community, says Diggs John Quinn. These changes reduce the incentive to post spammy content or link spam to Digg, while still flowing search engine juice freely to quality content.Digg is now adding relnofollow to any external link that they arent sure they can vouch for. This means External links from comments External links from user profiles External links from story pages below a certain threshold of popularityThis work was done in consultation with leading experts from the SEOSEM and link spam fields, in an effort to lookout for the interests of content providers and the Digg community, says Quinn.