The newly named iOS 4 was first properly announced back in April, but hasn’t yet been released. It’ll launch with the brand new iPhone 4, which was announced today at Apple’s WWDC keynote. If you need a quick recap of what it’ll do over the current operating system, look no further...

-------------------------------------------------------------------
Related links:
- iPhone 4 UK release date confirmed
- Apple iPhone 4: Our live coverage of the announcement
- Apple iPhone 4 specs: the full details revealed
- Apple iPhone 4: The story so far
----------------------------------------------------------------------

Multi-tasking

Outlining the fact that multi-tasking the wrong way 'can drain battery life' and make your phone feel sluggish, this most wanted feature is broken down into seven key service areas. 'Background audio' will let you listen to music while doing other things, like searching out the track to buy on iTunes, for example.

VOIP is taken care of by new functionality that’ll let you receive calls even when a VOIP app (like Skype) is running in the background. Third in the multi-tasking queue was ‘background location' which will enable you to listen to satnav instructions while still listening to music. Completing the multi-tasking line-up are push notifications, local notifications, task completion, and fast app switching to swap between programs.

Folders

Folders will allow you to group together similar apps like games or productivity tools. Once created, folders will be automatically named depending on the category of the apps within. They can then be re-named manually. The new-look UI means you’ll be able to see up to 2,160 apps, as opposed to the current 180.

Enhanced mail

‘Enhanced mail’ means you can now check all your mail in one inbox, drawing together MobileMe, Yahoo and Exchange accounts into one place. This also includes fast inbox switching and the option to organize by thread.

iBooks

iPad favourite iBooks will now live on the iPhone as well, as Apple’s decided to integrate the e-reader app into the smaller-screened smartphone. You’ll be able to enjoy the literary contents of the iBook store and wirelessly sync you books between platforms.

Enterprise update

Business users will be pleased to know that new features have also been added to Enterprise, of which the most notable include support for multiple Exchange accounts, wireless app distribution and SSL VPN support for more secure networking.

Game Centre

In a bid to rival Microsoft’s Window Phone 7 plans with Xbox Live integration, Apple has introduced the ‘Game Centre’ which brings a strong social networking feel to your iPhone gaming. It basically translates as a means of posting achievements, viewing leader boards and inviting friends into games.

iAd

Lastly and perhaps most significantly (for apps developers at least), was the unveiling of iAd. A unique take on mobile advertising, the app within an app uses the multi-tasking capabilities of the iPhone 4.0 OS and Apple’s new favourite thing HTML 5 to bring interactive advertisements with embedded video and games to apps.

Apple will sell and host the ads, pocketing a tidy 40% of the revenue. On this innovative approach to the once annoying ad you never wanted to click on, Jobs said “What we want to do with iAds is deliver interaction and emotion." The iPhone 4.0 OS will be launched this summer and will be fully compatible with the iPhone 3GS and iPod Touch 3rd Gen, as well as the iPhone 4, which launches in July.