The use of social sign on buttons to get people to log into web based applications is pretty common and has become quite a norm but I am wondering if the same logic could be extended to mobile applications instead of requiring the user the sign up using an email address and password.
One of the concerns/constraints I can think about is the need to share information between the facebook app (lets assume Facebook is the social sign on method used here) but I am just curious to know why it really hasnt caught on as a one click login process in mobiles would be so useful.