BBC has those answers and more. Unlike running backs and home run hitters or hockey goalies, there is no Papal Hall of Fame. However, ongoing residence within Vatican national borders has been arranged. Jim Brown was not granted housing for his remaining life in Cleveland, (nor did he seek it), and Joe Montana no longer wears the uniform.
As was always the case, the Pope's name and number combination is retired.
On a serious note, it is unclear if Benedict intends and the Church intends for him to have any official duties running into retirement. Presumably he might preside over Mass at churches outside of the Vatican from time to time, while the question I wonder about is whether he will continue to allow audiences, health permitting. He would still be a figure of reverence within the Church, and presumably world leaders might seek out a chance for a visit, although the formal title "audience" might only apply to being accorded time alone with the new governing Pope. He remains fluent in several languages and a writer.