I don't think this is bad for Boston at all. I like Turiaf a lot - he's one of the better options we could get as a backup big man, he can defend, he hustles, he's tough, he fits into what we do.
Not sure Golden State would want Powe. I think we overrate the "they want the hometown boy" factor. Are we desperate for JJ Barea because he went to Northeastern? Is Chicago desperate for Tony Allen because he's local? It works with stars like Derrick Rose and Dwyane Wade, not for role players like Powe. I think his knee injuries are enough to make anybody, even his hometown team or his current team, think twice about paying for him. I still want to keep him, but I don't think he'd be the lynchpin of a deal. Of course, if Golden State really wanted to get Powe, I'd be happy to do a sign and trade sending Powe and TA for Turiaf. (I really don't care about Bellinelli). Then we resign Baby, and we've got a solid front court rotation of Perk, Garnett, Turiaf, Davis and Scal, and we can look for a 3/4 backup either with MLE money or in a trade involving Scal, Giddens, Pruitt.