It's part of a new SEO program that i bought for the site.
Basically those little icons give you the ability to reference the post you are linking it to... (confused yet?)
Digg's Website Definition:
(The site's cornerstone function consists of letting people vote stories up or down, called digging and burying, respectively. Many stories get submitted every day, but only the most Dugg stories appear on the front page. Digg's popularity has prompted the creation of other social networking sites with story submission and voting systems. The website traffic ranked 116th by Alexa.com as of June 21, 2010.)
So if your part of DIGG or FURL or any of the other ones, this is a quick way for you to reference the post..