I've been seeing so many trades this year that involve draft picks this year and then also include signs and trades of free agents and/or the absorbtion of salary utilizing cap space. Those trades are impossible.
The draft is in June. The season doesn't turn over until June 30th at midnight. Free Agents can't be signed until the second week of July. In other words, the earliest Boston could have cap space or sign and trade a free agent is July, which is after the draft. So trades where Boston gets #10 and Okafor with no salary going to New Orleans, are impossible. Likewise Boston can't trade 21 and 22 with Allen or Bass to some team to move up in the draft. Now you could always trade the players drafted in a move in July (so if Boston gives up its rights, gets cap space, it could then trade for Okafor and whomever New Orleans drafted, but that can't happen until long after the draft), but those players have to be signed and thus their contracts have to be accounted for (it also means you actually have to want the player that some other team drafted).
Just thought a post on this might be useful since there have been a lot of proposed trades that just aren't feasible of late.