Celtics guarantee at least one "superstar" for their cap room next summer. Also get Hill (25) and Mayo (24) to strengthen the bench or start depending on what lineup they choose. I don't see either breaking out into an unreal season so Mayo could be signed for the MLE and Hill for probably $2.5 to $4 million a year after this season (both are free agents in 2012).
Indiana is a very good team, but adding two guys who can create their own shot (which they lack) will help them. Specifically Amare because he can score from the low block. He's a terrible defender, but Gay has enough length and athleticism to defend (although naturally not great on that end). Also, Hibbert is a solid defender to hide Amare's deficiencies. Overall, while giving up Granger, who has been the cornerstone of that franchise for a while, is tough along with Psycho T the Pacers need to improve their offense. Collison will get both of these guys involved, specifically Amare, which is partially the reason he's been awful in NY this year.
Memphis improves defensively with Granger and with Randolph out they upgrade their front court with Bass. They were better off without Gay last year and anticipating Randolph's return will move the scoring load to Randolph/Granger. Giving up Mayo is tough, but I don't see him staying in Memphis after this season anyway.
Obviously the Knicks lose their two best players, but at this point they need to understand the Melo/Amare experiment has failed. Building around Rondo will help them and Pierce is a veteran presence to help facilitate Shumpert, Fields, Psycho T, etc. They would have more depth on their roster, a top-5 point guard in the league and be much better defensively. They would need to target another scorer in the draft or free agency. Obviously with the two first round picks they have some leverage to move up in the draft or trade for someone if they feel they can't someone they want.
Celtics receive:
Carmelo Anthony
O.J. Mayo
George Hill
Indiana receives:
Amare Stoudemire
Rudy Gay
Memphis receives:
Danny Granger
Brandon Bass
Celtics 2nd round pick
New York receives:
Rajon Rondo
Paul Pierce
Tyler Hansbrough
Celtics 1st round pick
Indiana 1st round pick