A new operating system for a new iPhone. iOS 4 will bring a host of new software features to iPhone 4. The operating system is now named iOS rather than iPhone OS, as it powers the iPad and iPod touch, as well as the iPhone.
As the grand finale of his WWDC keynote, Steve Jobs placed a video call on his iPhone 4 to Apple designer Jonny Ive. The new video-call feature is called FaceTime, and it's a bit rubbish: it only calls other iPhone 4 handsets and it only works over Wi-Fi. Still, deals with 3G networks are on the cards, you can use front and rear cameras, and you can call in portrait or landscape view.
We saw a number of features in iOS 4 at the launch earlier this year. Folders allow you to sort your apps in your home screen and on your dock. Multitasking lets you swap between apps without losing what you're doing, and there are improvements to email, with a unified inbox and threaded mail. For some reason, PDF attachments get treated as ebooks and are filed on the PDF shelf of your iBooks library.
Microsoft's Bing search engine has been added as a search option next to Google and Yahoo.
iBooks wirelessly syncs your bookmarks, notes and where you're up to in your ebook across your different Apple devices. You can download copies of an ebook to your iPhone, iPad and iPod touch without any extra charge.
Jobs also showed off iAds, which is set to make money for the crowd of developers at WWDC -- they get to keep 60 per cent of ad revenue -- but may not be so welcome among iPhone users.
Adverts are embedded in apps in iOS 4, so, if you tap on a banner ad, you won't be taken out of the app to the browser. Instead, the advert will go full-screen or play an animation or video, like the Nissan advert pictured above. You can tap in the corner at any time to close the advert.
If you want to get in on the iOS 4 action on your iPhone 3GS, iPhone 3G or iPod touch, you can upgrade for free on 21 June. That's the first time an OS upgrade has been free for iPod touch users. Hurrah! Thoughts in the comments section below, operating-system fans.
Even more information
Apple iPhone 4 preview
iPhone 4 on O2, Orange and Vodafone
iPhone 4 poll: Will you be buying it?
iPhone 4 official picture gallery
iOS4: iPhone operating system gets new name and video calling
FarmVille, Guitar Hero coming to iPhone
iPhone 4: What we didn't get