Anderson Silva recently told a Brazilian cable channel SporTV he is pondering retirement within the next year. The full interview has not been released, but a source from the cable channel claims Silva talked about retirement multiple times during the interview. Fighters are known to say crazy things at times. I would not put much stock into this story. I do not dispute he said it. I just think it's a hypothetical situation and not some thing he is realistically planning for. As long as there are big fights for him, his manager will get him to fight.
Update - Silva's manager, Ed Soares, has put to rest the retirement talk. According to him, Silva has six fights left on his UFC contract. He also said they have an incredible relationship with UFC President Dana White. MMA news has been ridiculously light the past couple weeks and it is at those times when dumb stories like this tend to come out. All you Silva diehards can stop worrying now.