The latest version of Apple's iPhone software, known as iOS 4, is expected to hit iPhones and iPod touches on Monday, just three days before the official launch of the iPhone 4.
Apple has not announced exactly when the free download will be made available, though it will reportedly start around 10am Pacific time. The iOS 4 section of the Apple Web site currently has a "Coming Soon" banner.
The updated OS, which Apple first announced in April as iPhone OS 4, adds over 100 news features, including the company's new iAd platform, multitasking, background task completion, and background location. The OS was re-named iOS 4 last month when Apple unveiled its iPhone 4.
The update will be available on the iPhone 3GS, the iPhone 3G, and the upcoming iPhone 4, Apple said on its Web site. Certain new features, like multitasking, will only be available on the iPhone 3GS and iPhone 4.
Apple said iOS 4 will also be available on second- and third-generation iPod touches, but the second-generation will have somewhat limited capabilities. Multitasking, custom wallpaper, and Bluetooth keyboard support will only work with the third-generation iPod touch – the 32GB and 64GB models released in late 2009.
One of the more hotly anticipated features of iOS 4 will be multitasking, which will let you listen to music on Pandora while playing a game, for example. A new multitasking bar will display open apps, which can be accessed via double tapping the iPhone home button. Apps will freeze when you leave them, and start back up when you return.
Apple noted, however, that multitasking will only work with apps that have been developed to work with iOS 4, so there might be a limited selection at launch.
Also on tap for iOS 4 is iBooks, the company's e-reading platform that's currently available on the iPad tablet. Virtual books will be displayed on a bookshelf interface just like the iPad version, and Apple will sync books between the devices should you be reading the same book on the iPad and the iPhone.
Other features include folders, a unified inbox, playlists, 5x digital zoom, home screen wallpaper, and Faces and Places in Photos for those with iPhoto on the Mac.
Before the iOS 4 update hits your device, check out PCMag's extensive coverage of the update:
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