Apple has previewed its iPhone OS 4 software today, with a beta version released to iPhone Developer Program members. New features include multitasking for third party apps, folders to organise apps, improved mail with a unified inbox for multiple accounts and iBooks, the ebook reader and online bookstore that was recently launched on the iPad.
In addition, Apple announced a mobile advertising platform called iAd. It works within applications, displaying full-screen video and interactive content without ever leaving the app. Apple will sell and serve the ads, paying developers 60% of iAd revenue.
iPhone OS 4 will be available as a software update to iPhone and iPod touch users this summer, with an iPod version available in the autumn. However, some features won't be available on all products; multitasking isn't available on non-3GS iPhones or the 2G iPod touch.