Last I read, he hurt his knee. I'm not sure if he's still injured, though.
I actually feel kinda bad for him being traded, which is ironic since I was so against signing him. Sure he sucks but he was genuinely happy when he joined the team and was also genuinely happy when the Spurs won the championship last year. And his suckiness wasn't as a result of not trying or not caring. He practiced and worked on his game non-stop while he was here.
He's basically a late bloomer who never bloomed all the way. I hope he can stick around the NBA for a couple more years. He'd actually make a decent backup center for an athletic running team like the Warriors or the Bobcats.