It had to happen sooner or later: the CIA kidnapped and "interrogated" the wrong guy. This poor bastard's name is Khaled al-Masri. According to the lawsuit he filed against the CIA, al-Masri, a German of Lebanese descent, was leaving Germany for a New Year holiday in Macedonia when he was stopped at the border and arrested. He claims he was held for 23 days and then flown to Afghanistan (quite the vacation hotspot, I hear) where he was subjected to "torture and other cruel, inhuman or degrading treatment" at the hands of the CIA for five months. Eventually, the CIA confirmed his identity and decided they had the wrong guy ("Sorry about that, our bad") and then flew him to Albania of all places. Clearly, we don't know what happened in Afghanistan or what he considers "torture", but I'm pretty sure he wasn't given nightly back-rubs and gentle words of encouragement.
Obviously, this is one case, and I don't think policy should be decided on what may or may not have happened to one person. But this incident must surely give one pause. Even if you don't consider the morality of this policy to be a problem, there could be pragmatic implications: Are these renditions providing enough actionable intelligence to justify such terrible publicity? Could this policy cause our European allies to rethink their commitment to assist us in other intelligence gathering operations in their own countries? It's not outside the realm of possibility: The Europeans certainly aren't required to assist us, and in general, they feel far less threatened by Islamic terrorism than we do. Just food for thought.