I don't know if anybody knows about serving DL on tap. Hopefully they set up some extra tents to serve it. If not it is pretty amazing that Surly can serve Darkness during their whole event and still sell more bottles pf Darkness than 3F does of Dark Lord...
Some photos on a thread on BeerAdvocate show them setting up tents in the empty lot across the street from the brewery. There should be much more space this year than in years past!