I wouldn't be so sure this was orchestrated. The Cavs, I'm sure, had to believe Z would re-sign with them, but they wouldn't go so far as risk talking about, a la the Mavs. They could have ended up not getting Jamison at all, in that case.

A few clarifications, with some help from Larry Coon's Salary Cap FAQ: the 30-day restriction only applies to signing with the team that traded the player away, and the 30 days is counted from the date of the trade, not the date the player was waived. There is no waiting period to sign with any other team; the player can sign with any team other than his old one as soon as he clears waviers. (The restriction is actually 30 days during the season, but 20 during the offseason. It rarely seems to come up during the offseason, though.)

The 30-day restriction was added in 2005. Before that, there was no resriction, and players in this situation would sometimes return to their old teams within a few days of being traded, as soon as they cleared waivers. A few examples from that era are Gary Payton in 2004-05 (traded by Celtics to Hawks, waived, immediately returned to Celtics) and Lindsey Hunter in 2003-04 (traded by Pistons to Celtics, waived, immediately returned to Pistons).

IIRC, this type of thing first started to appear back around the mid 1990s. To Gary's point, it's obviously a product of the salary cap rules around trades. There is no practical reason to include the player in the trade. The team trading the player doesn't really want to trade him, and the team receiving the player isn't particularly interested in acquiring him. But he has to be included to make the salaries match up on both sides of the trade.

Phil Jackson and Doc Rivers are only complaining because the Z trade benefits a title contender. I think another trade happened this season where someone was bought out and returned to his old team, but no one cared because it wasn't an elite team (and also why I don't remember the details). Doc wasn't complaining a few years back when he benefited from a similar deal. And the Pau Gasol trade, though not constructed the same way, was also a trade of talent for financial relief (though now we see it wasn't so one-sided as we thought). As long as players are paid salaries and teams are businesses trying to make money, there will always be trades for financial relief instead of talent. No matter how salary cap rules are changed, teams will always find loopholes to exploit; there's too much money at stake.