Apple is scheduled to release iOS 6 later today Sep 19, 2012. iOS 6 contains more than 200 new features, such as new Maps app, improved Siri, Facebook integration, Shared Photo Streams, Passbook and FaceTime over cellular. Check out the official what’s new page from Apple.
iOS 6 is a free upgrade and is for iPhone 3GS, iPhone 4, iPhone 4S, iPad 2, iPad 3 and iPod touch 4th generation. Notable missing devices in the supported list are iPhone 3G, iPad first generation and iPod touch 3rd generation. iPhone 5 and iPod touch 5th generation to be released on Sep 21 will come with iOS 6 preinstalled.
You can as usual update to the latest iOS using iTunes on your Mac/PC. It is advisable to upgrade to the latest iTunes 7 before the update. Please ensure that you complete a backup of your device using iTunes before the iOS 6 upgrade.
If your supported iOS device is already running iOS 5.1, you can upgrade to iOS 6 wirelessly using Over-The-Air OTA method. Please ensure that you are on a WiFi network for the upgrade. Check that you have a recent backup to iCloud before the upgrade. iCloud backup is at Settings > iCloud > Storage & Backup.
Apple as usual do not reveal the release timing. In the meanwhile prepare yourself by upgrading to the latest iTunes 7, and backup your iOS device using iTunes and the iCloud.