Apple has succeeded in making iOS 5 beta 3 for iPad, iPhone and iPod touch that is now available for developers. You can excitedly download iOS 5 beta 3 ipsw from developer portal if you are registered in developer program. Links are available for non-developers in order to download iOS 5 beta 3 that is applicable for iPad, iPod touch, and Apple TV and iPhone devices.
Before starting installation of iOS 5 beta 3, you have to get its UDID registered. Therefore, if you set your mind for iOS beta 3, search for UDID of your mobile device, make registration and then proceed further to download iOS 5 beta 3 ipsw.
Be sure that beta firmware is not for non-developers who do not have any knowledge about firmware beta. There are online scams that grasp your money by offering you the UDID activation, do not answer back to them.
To upgrade your iOS device to iOS 5 beta 3, you need iTunes 10.5 beta 3. Without iTunes 10.5 beta 3, you will fail to get iOS 5 beta 3 ipsw, so download new iTunes and then start the upgrade process.