iOS 5 was recently rumored to have Twitter integration built-in. From what Apple is showing today at WWDC 2011, there will now be a new feature they're referring to as a "tweet sheet" that integrates into "Twitter friendly apps".
We aren't really sure what Apple is considering "Twitter friendly" at this point. I'm only assuming there will be available APIs that make it possible for developers to integrate Twitter into their apps natively (without third party permissions hopefully?). This functionality will be really amazing if it integrates with stock apps like Photos. Say goodbye to having to upload pics to Twitter via third party sites.
[Image via Engadget]