We have all seen studies that make recommendations to avoid some foods. Later, we see other studies that recommend their consumption. This is no different. Long thought to cause a variety of health problems, coffee has actually begun to show up in recent medical reports as being beneficial to our health. The key thing is moderation. This article is interesting in that it describes that, although there can be some deleterious effects on teeth (such as staining), coffee also has some benefit. So, drink up!
(The study that this story references was done by a Professor of Biochemistry at my Alma Mater, the University of Maryland School of Dentistry.)