Facebook and Twitter have become two of the most common identity authentication services. Many web services now let you login to their system using your Facebook or Twitter login authentication. What are essentially side-effect add-ons to these social networking services have succeeded where dedicated identify efforts like Microsoft’s Passport and Open ID failed.

Some of have said Twitter’s integration into Apple’s upcoming iOS 5 makes it the default identity server. However, so far, that does not seem to be the case. A Twitter account does not, for example, will not be your authentication for iTunes or the online Apple Store.

However, it is clear that Twitter will be the default social sharing service for the iPhone and iPad with direct tweeting available from within Apple’s Safari, Photos, Camera, YouTube and Maps apps. Twitter also works directly with the Contacts app to provide the Twitter address for an “@ reply.”

Apple iOS 5 Features: Twitter Integration