Thank you IM pfren for Watson's interesting review of Muller and Voight's "Danish Dynamite". Both authors of the book, as well as Grandmaster Tim Harding, say the Danish Gambit has not been refuted. Although I have not made it through Watson's analysis; I gather he must disagree with them.
I also recently read a comment by a German Grandmaster who also said the DG had not been refuted; but as I said before I have not been able to find that reference. If anyone else knows about that reference I would appreciate your posting it. Thank you.
See here:
http://www.chess.co.uk/twic/jwatsonbkrev62.html
The first mentioned line is virtually a refutation of the gambit, but first you must repair the holes in Watson's analysis- there are plenty of them in there!