Apple today previewed its iPhone OS 3.0 software and announced the immediate availability of a beta software release to registered developers. The iPhone OS 3.0 beta release includes an updated Software Development Kit (SDK) with over 1,000 new Application Programming Interfaces (APIs) including In-App Purchases; Peer-to-Peer connections; an app interface for accessories; access to the iPod music library; a new Maps API and Push Notifications.

How you go about developing software for mobile devices depends primarily on which platform you intend to develop. While there are many large players competing in the the mobile platform market, there doesn’t seem to be an obvious winner.