Just found this haven't tried it yet here's how to get iOS 5


Here are the steps:
1. Download the iOS 5 IPSW file from the web (its easy and readily available. Just Google it and torrent it down).
2. Update your iPhone using iTunes. To do this, connect your iPhone to your computer, click on the Check for Update button with the Option (Mac) or Shift (PC) key pressed. Select the iOS 5 IPSW file from the place you downloaded it to.
3. Wait until it upgrades. A new activation screen will appear.


Activate iOS 5
1. Triple click the home button. This will activate the Voice Over.
2. Triple click the home button and Emergency Call will appear.
3. Click on Emergency Call and, while its switching, swipe with your three fingers down.
4. The Notification Center will appear!
5. Click on the Weather widget. The Weather app will load.
6. Click on the home button to exit to the iPhones springboard.

iOS 5 beta is not a finished product. In fact, it isnt even a late beta release. Therefore, upgrade at your own risk.

iOS 5 Downloads: [ Register or Signin to view external links. ]

Edit: added link to iOS downloads