Donnie Walsh talks to Chad Ford on his podcast about the trade. (I don't know how to directly link to it, but it's on the right side of the webpage with the title Daily Dish: Behind the Big Deal)
-The reason the trade was kept so quiet was because only Walsh, Bird, and Mullin knew about it/were discussing it. So there was no one else to leak information.
-Rick Carlisle didn't know about the trade until the morning it was done.
-Donnie says he's "definitely not" going to trade Dunleavy for Maggette. The rumors are "absolutely not true." He sounds pretty definitive here. No wiggle room or "We're not shopping Jalen Rose" kinda talk.