The Pistons won't use their amnesty provision this year, a source tells TNT's David Aldridge (Twitter link). As I noted in our amnesy primer, Charlie Villanueva and Greg Monroe were Detroit's only remaining eligible players, and Monroe wasn't going anywhere, so this news essentially means that Villanueva is safe.
Aldridge notes that the likely reason for the decision is to ensure that team salary exceeds the required $52.8MM floor, but the salary of amnestied players still counts for floor calculations, so I don't think that's it.
Perhaps Detroit simply just has little incentive to pay Villanueva to play elsewhere, especially since the cap room the move would create probably wouldn't be used to sign anyone else. When you take into account all the players the Pistons have signed or will sign, plus their drafted players, there are 17 guys in the mix for 15 roster spots, so further additions seem unlikely. Villanueva's expiring $8.58MM deal could also be used to facilitate a trade later on in the season.
Because Villanueva and Monroe are both entering the final year of their respective contracts, this decision, if it's final, means Detroit won't use its amnesty clause during the course of the 2011 CBA.