So Apple’s iPhone OS 4.0 event is underway, and of course the first big news is that a developer preview of iPhone OS 4.0 will be released today with shipment this summer reports the live coverage thanks to the guys at gizmodo.

Of course what everyone has been waiting for is multitasking which Apple has listened and will come with iPhone OS 4.0 with them saying they weren’t the first to the party but will be the best, and apparently when the multitask tray pops up it pushes the user interface higher.

There were demos of Pandora running in the background, VoIP a Skype demo, background location, push notifications, task completion, and fast application switching leaving everything preserved in the background.

There are also folders in which to arrange your apps which is done by dragging one app on top of another and a folder is automatically made with no limit on folders and can even place folders in the dock. A user can now have 2160 apps on their iPhone if you replace ever 180 app spaces with a folder.

Moving on to enhanced email, a unified inbox along with more than one Exchange account, and you now get the ability to open attachments with 3rd party apps from the App Store. There is now iBooks support with the bookshelf looking similar to that on the iPad.

As for Enterprise features, better data protection, and encrypts emails and attachments and APIs so devs can encrypt gear inside their own application.

Now we move onto what they call “Game Centre” and here’s a biggie, they are adding a social gaming network where you can challenge a friend to a game along with automatic matchmaking that finds random people to match up with you in multiplayer.

As for mobile advertising they are building it direct into iPhone OS 4.0 with iAd inside the OS. Jobs says it’s the better way to deliver ads, inside apps rather than in search. Apple will host and sell the ads and give 60% of the revenue to the developer.

So that’s what went down in the opening hour of the Apple iPhone OS 4.0 event today which gizmodo are running a live blog on so please drop by and check it out.