I hate to say this, but it looks like Christopher. I played it back a few times frame by frame, and it looks like him. In the scene, Christopher's Hummer is in the background, but he is not one of the 4 men standing there. Also add Adriana's final comment in the trailer. Of course I could be 100% wrong since the trailers are almost always misleading. [/b][/quote]I dont think it is Chris that Tony shoots because in the review for April 18 says this:

Episode 7-In Camelot: Tony learns about lingering emotional and financial mysteries from his father's mistress; Junior sees the benefit of attending funerals; Christopher enables a friend's addiction

So we know Chris doesn't die yet. Also if you look in that scene where Chris's Hummer and the guys standing around Tony, I think that is Christopher right behind Tony. I'm guessing that since it is Tony doing the killing, it must be personal. My guess... Tony's Capo, Raymond Curto. Then again, who the hell knows!