As the other two posted, Derm is uber-competitive, even for the best MD applicants...
However, I know of one, and from the grapevine, two or three more DOs that matched MD Derm this past Match season (2002-2003). It IS possible but i am sure that there were extraordinary reasons for a few DOs to grab MD Derm spots (i.e. incredible fellatio skills).
Q, DO