Skipping the traditional spring unveiling, Apple used part of its WWDC 2011 keynote to show off what’s coming in the next generation of its mobile devices, namely the behemoth that is iOS 5. Here’s what’s new, and when to expect it.

Following a demonstration of 10 features for Mac OS X 10.7 Lion, Apple Senior Vice President of iOS Software Scott Forstall took the stage to talk iOS 5, available this fall. After a volley of the usual facts and figures about how the platform is faring, Forstall cut to the chase and started talking about 1,500 new APIs that developers will have to tap into, with 200 new features to end users, 10 of which are being shown today.

First and foremost is a new notifications system for iOS 5, bringing one of the longest-standing complaints about the platform to a grinding halt at last. “We have built something that solves some of the current problems,” Forstall reveals, announcing a new Notification Center that gathers this information in one easy-to-use spot which is accessed by swiping from the top of the screen. Notifications will also be featured on the lock screen, where you can swipe across any of them to go straight to the app in question.

Newsstand finally brings all of your magazine, newspaper and other periodical subscriptions to one place. “When you purchase them they’re automatically downloaded and placed on the Newsstand,” Forstall explains, showing off an integrated “newspaper stand” type graphic on the home screen.

Number three: Twitter. Yes, you’re reading that correctly -- the rumors of deep Twitter integration into iOS 5 appear to have come true. There will be a single sign-on location in the iOS Settings and the feature will be integrated with apps such as the Camera and Photos for quick sharing.

The distraction-free Reader view in desktop Safari is finally coming to Mobile Safari, which certainly poses a threat to existing services such as Readability. Reader for Mobile Safari will allow you to email the contents of a story as well as the link, and the browser will also gain the much-rumored Reading List feature similar to Instapaper. Last but not least, tabbed browsing finally comes to Mobile Safari as well. “It is lightning fast to switch between windows now,” Forstall exclaims. Potentially putting another class of third-party developers out of business, Apple will introduce a slick new Reminders feature to iOS 5 which syncs across devices as well as to iCal.

At long last, iOS 5 will finally introduce a dedicated Camera button on the lock screen for quick one-tap access, and Apple has finally allowed use of the volume up button as a dedicated camera shutter, much to huge applause from the audience. The Camera app also gains an auto exposure and auto focus lock, pinch to zoom and the ability to do basic editing such as crop, rotate and red-eye reduction without leaving the app.

The iOS Mail app now gains rich text formatting, indentation control, draggable addresses, entire content searching and the ability to mark emails as unread if you want to act on them later. Security is also getting a boost with the use of S/MIME, and there’s finally a built-in dictionary that’s now a service across the entire iOS platform as well.

Number eight: PC Free. Finally! iOS will no longer require ties to the computer. “We know we’re selling to a lot of places where the households just don’t have computers,” Forstall confesses. Now you’ll be able to take your device out of the box and setup/activate right on the device. Software updates will also now come over the air, and they will be in the form of “delta” updates with just the new bits, rather than having to download hundreds of megabytes each time.

Game Center will also get some love in iOS 5. “iOS is the most popular gaming platform on the planet,” Forstall boasts. “There are more than 100,000 game and entertainment titles in the App Store.” Citing more than 50 million Game Center users in only nine months -- eclipsing Xbox Live’s 30 million users in eight years -- Forstall promises that the service will get even more social with friend and game recommendations and even the ability to purchase and download games directly from the app.

Last but not least, Forstall introduced the new iMessage service for iOS users, supporting all of the company’s devices. Users can send text messages, photos, videos, contacts and group messages with delivery and read receipts as well as real-time typing notification. Start a conversation on your iPhone and pick up where you left off on the iPad, and it works over both 3G and Wi-Fi.

Among the other features coming to iOS 5 are AirPlay mirroring, wireless sync with iTunes (hooray!), multitasking gestures and much more. iOS 5 is being unleashed to developers via an updated SDK today and will ship to customers in the fall alongside the free iCloud service, with support from the iPhone 3GS and up.

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