The iCompany, Apple has built Twitter into iOS 5, essentially making it the default social graph and social network on iPhone, iPod Touch and iPad.

“We hear from a lot of our customers on iPhone, and iPad and iPod Touch that they love Twitter, so we want to make it even easier for all of our customers to use Twitter on iOS products,” Apple’s Scott Forstall said during the WWDC 2011 keynote.

When iOS 5 is released this fall, device users will able to sign in to their Twitter accounts once and then tweet with a single tap from Apple’s applications — Camera, Photos, Safari, Contacts, YouTube and Maps — and third-party applications that support the single sign-on capability.

Apple’s complicated relationship history with Facebook paved the way for its new intimate romance with Twitter.

Facebook is in no way integrated in iOS 5, nor is its familiar blue logo anywhere to be found in Apple’s promotional materials. Twitter, by contrast, is everywhere. It will soon be the social layer of iOS, enabling users to turn individual actions such as snapping a photo or reading an article into instant social activities.

“Building Twitter into iOS 5 truly creates the easiest way to share everything that’s happening in your world. Take a picture, tap ‘Tweet,’ ” Dorsey said of the news. “Tweeting has never been simpler.”

The implications are vast. Twitter will essentially become the default social network for iOS users.