I didn't think the Phillies are selling right now, but if they did it would certianly require Kevin Youkillis, who could be the Phillies 3B of the future, but problem with that is he most likely would be the Red Sox 3B next year.
The Red Sox would probably offer Kelly Shoppach, Manny Declarmen, and doubtfully Jon Lester. The third player might be an Abe Alvarez? So it would give the Phillies a catcher, a potential elite setup man, and a 4th to 5th starter. But trading Wagner would give the Phillies a ton of backlash in the press, so I don't think they'd move Wagner.