Upgrade to iOS 6 Right Now

Although iOS 6 won't see an official release until September 19th, you can install the final version right now even if you're not a developer thanks to some anonymous public postings of the software update files. Here's how.
Note: We updated a handful of iDevices using these files and encountered no issues, but because we're unable to verify them all we don't know problems won't arise. This process worked for us when we tested with an iPad, and iPod touch, and an iPhone, but there's always a chance you could run into an issue. Please be aware that there's some risk involved before you upgrade.

Backup First!

Before you do anything, back up your iDevice with iTunes. In the past, the early upgrade process worked for some but not for everyone. The results may be the same this time around, though we've upgraded to the final version of iOS 6 without issue. Regardless of whether or not things work out you will need to restore your device so back it up!

Download iOS 6

Thanks to a public posting on RapidShare, you can download the Golden Master version (essentially identical to the final release coming next week) of iOS 6 for your device without logging into the Apple Developer Center. Here are the download links. Choose the type of device you want to update:

• iPhone 4S
• iPhone 4 (GSM)
• iPhone 4 (CDMA)
• iPhone 3GS
• iPad (3rd Generation) with Wi-Fi
• iPad (3rd Generation) with Wi-Fi and Cellular (AT&T)
• iPad (3rd Generation) with Wi-Fi and Cellular (Verizon)
• iPad 2 with Wi-Fi Only
• iPad 2 with Wi-Fi (Rev. A)
• iPad 2 with Wi-Fi and 3G (GSM)iPad 2 with Wi-Fi and 3G (CDMA)
• iPod touch (4th Generation)

The iOS 6 update may require a later version of iTunes than you have installed. Update your copy before moving on.

Install the Update

To install iOS 6 on your device, follow these instructions:

1. Open up the disk image (.dmg) and find the iPhone Software Update file (.ipsw) for your device. Drag it to the desktop, or a folder of your choosing. (Windows users will need a tool like 7-Zip to do this, and will need to open the .hfs inside the .dmg as well.)
2. Open iTunes and connect your iPhone, iPad, or iPod touch, to your computer.
3. If your device isn't automatically selected in iTunes, select it and go to the "Summary" tab.
4. Hold down the option key (OS X) or the shift key (Windows) and click the Restore button. Browse to the .ipsw file you downloaded, select it, and wait for the update to finish.
5. If necessary, restore your device from backup and sync with iTunes.

That's it. If you follow those steps, you'll be up and running iOS 6 in no time.

via Lifehacker