3:12pm: The Clippers and Celtics haven't talked for several hours, sources tell Adrian Wojnarowski of Yahoo! Sports (Twitter link). However, Wojnarowski reports that the Clips would still like to get the deal done and are working on ways to satisfy the league's concerns.
1:00pm: Sam Amick of USA Today suggests that for the deal to be completed, one of two adjustments may have to be made. The Celtics may have to give up something more in the deal along with Garnett, most likely draft picks; or the Clippers may be able to give up slightly less.
According to Amick, the NBA believes that the "mere appearance that there is value being attached to Rivers" is not in accordance with the CBA, so it's Garnett's trade value that should be at the center of the discussion, rather than Rivers' value.
12:52pm: The league's primary concern with the proposed Celtics/Clippers deal is that the CBA doesn't allow coaches to be traded, as Broderick Turner of the Los Angeles Times writes. Breaking it up into two separate moves would still be frowned upon by the NBA, a source tells Turner, since the Clippers are trying to get Rivers more than anything else.
The league has told the two teams for "several days" that the deal as currently constructed isn't legitamite, so the two sides are working to come up with an alternate solution, according to Turner.
12:26pm: Appearing on The Herd with Colin Cowherd on ESPN Radio today (video link), commissioner David Stern confirmed that the NBA wants to ensure the Celtics and Clippers aren't violating the CBA by including a head coach in a trade or by making two separate deals that are contingent on one another.
"If we know that what the parties really wanted to do is one [deal] they're going to break into two for purposes of trying to avoid the restrictions that the Collective Bargaining Agreement places on it, we know how to deal with that," Stern said.
11:36am: Stein reports (via Twitter) that the Celtics and Clippers have begun discussing new trade scenarios in an attempt to satisfy the league's misgivings about the two deals.