Dempsie is currently a free agent after being released by Hibs (I think) and played the full 90 minutes in the victory. He had a decent game, and according to Chic Young on the radio the deal will be finalised in the next few hours.
If he continues putting in performances like todays then he'll be a good signing. If he does sign, he can't play against Celtic next week due to the 14 day cup rule.