Once you install an app with Twitter integration in iOS 5, you’ll see a single dialog box pop-up asking you if you’d like to connect the app to Twitter. This will look a lot like the pop-up that asks if you’d like an app to be able to use your location, Sarver said. Click, “OK” and you’re good to go. You’ll never be asked to enter a login/password or anything else. Nor will you see the pop-up box in that app ever again.
That is going to be huge.