It does, but then it downloads some CD-sized thing, which you can cancel at any point. I have clicked update once. After slowly fetching the update, the downl

It does, but then it downloads some CD-sized thing, which you can cancel at any point. I have clicked update once. After slowly fetching the update, the download was corrupt, and iTunes wanted to pull the entire thing down again. Slowly, of course. So I canceled, and haven't accepted any updates since, but iOS 5 might be worth trying again.