martinibuster - 3:42 am on May 27, 2011 (gmt 0)

Does this mean that If nobody is tweeting about a site or any of its topics, It is a shallow site?

Probably not. The lack of tweets might not count against a site. But if site X is the recipient citations from a wide variety of tweets then it's possible/feasible/reasonable to take that as a positive signal about the content on site X.