How about this one:
Why NYK does it: For 'Melo, and for the financial flexibility of acquiring him without having to take back Al Harrington, thus making signing Chris Paul in the future a possibility
Why DEN does it: If they really think they're losing 'Melo for nothing, this trade nets them an immediate $5 million in cap savings, rids them of their worst contract, rids them of another player they may lose for nothing this off-season (Nene has a player option and wants out), lands them an additional pick (or two) and lands them a young prospect in Chandler who could step in and be the future of the team right away. It's not a great deal for one of the NBA's best offensive players, but at least they're not losing him for nothing.
Why IND does it: To address both of the team's biggest needs before all of the expiring contracts become irrelevant. Fields has a high ceiling, and while he's not the offensive player that Rush, or even Dunleavy is, he's young, tough, a good defender and rebounds very well from the position. PF gets a complete overhaul with Nene (who'd be a great fit here, now that he's sort of proven he can stay healthy) and if he splits at the end of the year, Anthony Randolph becomes the consolation prize.
DEN-Billups/Afflalo/Chandler/Martin/Chris Andersen (when healthy) with JR Smith/Dunleavy/Walker/Sheldon Williams coming off the bench.
IND-Collison/Fields/Granger/Nene/Hibbert with Price/Rush/Harrington/George and Hansbrough or Randolph coming off the bench.
NYK-They'd be giving up a TON for pretty much just 'Melo. But if it meant they could possibly sign Chris Paul in the future, it'd be tempting. Still, if I'm Donnie Walsh it's hard for me to fathom a situation where I part ways with Wilson Chandler, Landry Fields, cash AND a possible future pick unless it means I'm obviously much better for it. According to John Hollinger, it doesn't make NYK any better (in fact, it only improves us).
DEN-They may think waiting for the 'Melo expiring money to clear up will be a better deal than doing this trade, where they really only get two great assets (Chandler and the Pacers pick), and neither are close to 'Melo-level in value. Also, they may need some NYK money too to pay off some of their over-roster-limit cheap contracts. They may also think a trade package of 'Melo for Curry/Chandler/Gallinari with a future pick would be more attractive.
IND-Aside from taking on Al Harrington's contract (again) It's tough to find one, other than the possibility that Nene may not want to re-sign. He recently said there were three teams he'd be interested in playing for next season, and while he didn't disclose them, I'm guessing Indiana wasn't on his list.