iOS 6 is now available. You can get it by plugging in your iOS device in to your computer and check iTunes for an update, or you can go into the settings menu on your iOS device then navigate to General > Software Update.
iOS 6 is supported on the following:
* iPhone (3GS, 4 or 4S)
* iPod touch (4G, 5G)
* iPad (iPad 2 or New iPad)
Click here for a round up of all the new features in iOS 6.