Digg has just announced in its blog http://blog.digg.com/?p=864 that external links to sites from "comments, user profiles and story pages below a certain threshold of popularity" will have a no-follow tag applied in order to reduce the spammy stories submitted to the social bookmarking site.
This is not a blanket no follow tactic, external links that prove popular will be reviewed with the possibility of having the no-follow tag removed, and so still be beneficial to your SEO link building strategy.
There are two main benefits to SEO PR and in particular "digging" your articles and news:
1. Increasing traffic
2. Building incoming links
This change will not affect good quality content submitted to the site with genuine intentions by a trusted and reputable source, but will give users a better experience by making the genuine content more visible to users, thus enabling more traffic to be generated.
In the changing face of search and the rapid innovations and developments we are reminded again that links are not the be all and end all of SEO, but good quality content submitted in the right places generating good traffic will be more beneficial to your SEO efforts, with the possibility of an added bonus in the form of a quality link.
Check this blog again soon for a follow up blog with guidelines on what makes good seo copy.