Apple recently released iOS 5 beta and iTues 10.5 beta. It is available only for Apple registered developers. But you can try it too. Remember that you do it at your own risk. Below you will find iOS 5 download links for iPhone 3GS,
Keep in mind that your iDevice will need to be activated, your UUID needs to be registered in Apple. Installing iOS beta on a non-activated device will render it useless. If you need help with registering UUID – write us, we will try to help..
Remember that currently there is no jailbreak for iOS 5 released.
You can download iOS 5.0 beta 1 and iTunes 10.5 beta