According to Mike Garafolo of the Newark Star-Ledger, the Eagles stole Maclin from the New York Giants.
Garafolo said that the Giants had a deal in place with the Detroit Lions to jump up to #20 and grab the Mizzou WR. The Eagles must have known about this deal. They had to. When I saw that they went to #19, I thought for sure it was for Brandon Pettigrew. The Lions need a TE terribly and they have no need to draft yet another WR. They already have Calvin Johnson and they've been down the "wide receivers in the first round" road before.
Garafolo says that the Giants are still happy with their selection of Hakeem Nicks and that they had him graded only slightly lower than Maclin. Time will tell who got the better end of this deal.