As expected, Twitter is going to be a big part of iOS 5. Apple's goal was to make Twitter easier to use in iOS 5, and it seems that they're going to succeed. In iOS 5, Apple has added "Single Sign On," a feature that allows you to login to Twitter directly from your Settings app.
Also as expected, Twitter has been integrated into the Photo and Camera apps. From now on, you can send pictures directly to Twitter without having to launch an app, or rely on a jailbreak tweak. In addition, you can tweet from Safari, from YouTube, or from Maps...