5:13pm: The Spurs have sent out a press release officially announcing that they've waived Jackson.
4:50pm: Jackson and head coach Gregg Popovich had been "sparring" about Jackson's role with the Spurs all season, according to Wojnarowski. The two sides discussed a potential release prior to the trade deadline, but agreed to move forward for the rest of the season. However, the disagreements resurfaced this week, says Wojnarowski (Twitter links).
4:24pm: With just over a week until the postseason gets underway, the Spurs have waived Stephen Jackson, according to Adrian Wojnarowski of Yahoo! Sports (via Twitter). It's not clear yet why the Spurs are parting ways with Jackson, but one source tells Wojnarowski that it's been "brewing for a few days" (Twitter link). Art Garcia of FOX Sports Southwest first tweeted word of the roster move.
Jackson, 35, hadn't been having a strong season on the court, with his averages of 6.2 PPG and 8.1 PER the lowest he has posted in over a decade. Nonetheless, given the timing of the move and his place in the Spurs' rotation, I would assume he's out of work for off-the-court rather than on-court reasons.
Jackson had been playing out the final year of his contract, earning more than $10MM this season. He won't lose any of that money by being waived, though he will hit free agency a few months earlier than expected. Since he was released after the March 1st buyout deadline though, he'd be ineligible for the postseason, making it unlikely that he catches on with another team next week.
As for the Spurs, they had been carrying a full roster of 15 players, so the move opens up a spot for a free agent, should they choose to make an addition.