Tweets abound that Mike Fucito and Possibly Mike Chabala for a left back. Rumor is it is a New Zealand Left Back but that most likely is incorrect as there is no New Zealander on DC's Roster. Unless they are trading with more than 1 team and sending someone to LA Galaxy for Andy Boyens.
If Portland is trading only with DC United I would expect a 2 for 1 trade and I am still trying to figure out exactly who that would be. Will get more information up as we get it.
UPDATE: Looks like Mike Chabala has been traded to DC united for a draft pick (Rumor is supplemental) but there is a lot more still to come out and no confirmation on the Fuctio rumor.