Downgrade iPhone 4 / 3GS from iOS 6 to iOS 5.1.1 | The iPhone FAQ
Do you miss Google Maps? Did the iOS 6.0 update shorten battery life on your A4 device? Whether you upgraded by mistake, or you're just looking to bring back the older firmware, now you can downgrade your iPhone 4 or iPhone 3GS to iOS 5.1.1. The following...