The CC0 waiver expresses that content posted on Digg is public domain even internationally. A minor point maybe, but our previous public domain dedication was only clear within the USA. When a friend from Creative Commons suggested that we move to a CC0 waiver, to even more clearly affirm our intentions, it seemed obvious. — Daniel Burka, former Digg Creative Director (http://about.digg.com/blog/some-small-important-digg-updates)
Digg is a social news website that highlights user-contributed content based on its popularity which is determined by readers voting up and down stories. Digg has waived all copyright restrictions on its content through the CC0 public domain waiver. Digg content may include readers' comments, story titles, story descriptions, and all other user-contributed content on the Digg site.
Digg waives all copyright restrictions to its content under the CC0 public domain waiver.
Previously, all Digg content was stated as in the public domain, but Digg went a step further by using the CC0 public domain waiver to ensure that its content would be available on the same terms around the world. See Daniel Burka's post from 2009 for more information.