You don't need to wait for an official release of apple before you install iOS6 on your device. Iphone developers show a way on how to do it. Below are the steps that you need to do in order for your device to be upgraded with the new version.
1. Make sure you have the latest version of iTunes (version 10.6.3) in your PC.
2. Download here the iOS 6 beta file for your device.
3. Unzip/convert the .dmg file to .ipsw
4. Open your iTunes.
5. Plug in your device (note: do some back up first).
6. Look/click for your device name on the left panel of the iTunes window, then in the main panel, search then click on the ‘Check for Update’ button (while holding on the option key).
7. Select the iOS 6 .ipsw file you have downloaded/extracted and install it (it will take few minutes to finish the installation).
Source: Iphone developers