Marc Gasol + OJ Mayo + 1st rounder for Dwight?
I'm not sure how the resigning of Gasol affects his contract and if/when he is tradeable. TradeMachine has his salary at $3M for some reason, but with throw ins, it still can work:
http://games.espn.go.com/nba/tradeMachine?tradeId=6qgnjug
I think if you're Memphis, you're too concerned to lose Dwight to make this trade. Marc Gasol is a very good player, and I think the risk doesn't outweigh the chances of reward.
On the other hand, I think the risk is worth the reward for Atlanta. Worst case scenario, they lose out on Josh Smith to get out of Joe Johnson's contract.