Apple has released iOS 4.0 (the renamed iPhone OS). Boasting over 100 new features, the free upgrade and can now be downloaded via iTunes. (connect your iPhone or iPod Touch to your Mac or Windows computer and click the Update button). Available for the iPhone 4/3GS/3G and the iPod Touch 3G/2G, the updated system offers a number of new features, including:

• Multitasking – Switch between apps instantly without slowing down the performance of the foreground app.
• Folders – Organize apps into folders with drag-and-drop simplicity.
• Improved Mail – See messages from all eMail accounts in a unified inbox.
• iBooks – Apple’s ebook reader / shopper.
• Custom playlists – Can now be created directly on the iPhone.
• Increased digital zoom – Now up to 5x.
• Home screen wallpaper – Change Home screen background.
• Gift apps – Send apps as gifts to your friends or family.
• Built-in spell checker – Works in Mail, Notes, and other selected apps.
• Universal wireless keyboard support – Any Bluetooth keyboard.

Note: Not all features work on all devices. Example, multitasking is available only on the iPhone 4 and iPhone 3GS. So, your mileage may vary.