Apple tonight demonstrated iOS 5, its next generation operating system for Apple iPad, Apple iPhone and iPod touch. According to Apple, there are  more than 1,500 new APIs and 200 new features in iOS 5. Interestingly, many of these replicate functionality already provided by third-party apps, ehich is unlikely to prove popular with Apple's software partners.

At the WWDC keynote in San Francisco tonight, Apple demonstrated 10 key new features as well as systemwide enhancements such as the addition of the iBook dictionary to all keyboards (Tap a word, you'll get a define option, and the dictionary panel pops up).

iOS 5 will be available to every device that currently uses iOS 4.3: iPhone 3GS, iPhone 4, iPad, iPad 2, third- and fourth-generation iPod touch. It will launch in the Autumn.

See also: Apple announces Mac OS X 10.7 'Lion' - full details

Apple also described a feature it called 'PC free'. In essence, Apple claimed, this means that iPads and iPhones no longer require to be synched with a desktop or laptop computer. Software updates and set up will take place over the air. The updates will now be incremental, so much smaller and easier to install. Apple said it had looked at iOS and tried to eliminate all reasons to go to the computer. So mailboxes can be added, photos edited, calendars added without having to use a PC.

Another feature was the Notifications Center: a single interface that combines all of your notifications, that you can reach from anywhere. It shows your missed calls, voicemails, text messages, any push notifications from the App Store... stocks and weather... any notifications, in fact. On the flip side, you no longer get interrupted by notifications.

Next Apple showed off 'Newsstand', a single interface in the App Store that combines all newspapers and magazines. It offers background downloads, meaning that users no longer have to remember to download a newspaper before they head out to work.  

Another new feature is built-in Twitter. A single-login takes you to all Twitter apps, the Camera and Photos apps are integrated, as is your device's GPS capability. It's integrated with Contacts, and you can Tweet from YouTube and Safari, as well as the camera.

Some enhancements to Safari for iOS were also announced. There's now an iOS version of Safari Reader, that brings articles into a single page, and lets you email the contents of an article.There's also Reading List: a simple and convenient way to save a story for later, that adds content to all your iOS devices as well as Safari on Mac and Windows. There's also tabbed browsing.

Apple has also brought a native 'Reminder' app into iOS. It keeps multiple lists and dates, and you can assign locations. So it will tell you to do something when you arrive at that place, or even when you leave.

The Camera app has been updated too. Apple has made it easier and quicker to take a photo from the locked home page. You'll also be able to take a photo by using the volume up hardware button, and can use pinch-to-zoom to zoom in with the camera. An optional grid can be used to compose snaps, and this release of iOS includes native photo-editing apps.

Apple has also added enhancements to the Mail app in iOS. There's rich text formatting, flagging, and full-text searching of mail - including those on the server. Support for S/MIME improves security for enterprises.   

Game Center is getting more social, with photos for profiles, and the ability to compare your gaming against friends. You can recommend games, and purchase and download games through the Game Center. Support for turn-based games is now built-in.

Apple finally showed off a IM service for iOS users: iMessage. iMessage works over 3G or Wi-Fi. If you start a conversation on one device it picks it up on an other. And it offers read receipts, and an indication of whether your contact is typing. Every message is encrypted.

Introducing the keynote, Steve Jobs said: "We're going to talk about three things today. If the hardware is the brain and the sinew of our products, the software is their soul."

The WWDC keynote in San Francisco was attended by more than 5200 attendees and, according to Apple, sold out within two hours.

Full coverage of the WWDC keynote's Jason Snell and Dan Moren contributed to this story.