John Gruber puts forward an excellent theory on Apple, the evolution of browsers, and what he feels is the real Web 2.0 revolution.
Definitely some interesting food for thought.
How many times are you asked to enter user-id and passwords in these mobile applications? Delegation is one of the methods in which you can authorize a mobile application to access your data in a cloud application.
If intelligent mobile and desktop client applications are the next 'thing', then OAuth will be a key requirement for handling authentication of intelligent client applications in enterprise applications.