It would appear Digg slipped in a slick little feature during one of the recent updates.

If a Digg submissions uses vulgarity in the title or description, it is changed automatically to show “*” and censor the word.

However, if you log into Digg, then you again see the vulgar term uncensored.

Example in comments:

Got to give it to Digg for making sure it’s users can be as vulgar as they want… once they are logged in.

Hat tip to Greg Hartnett, Best of the Web, for the find.