Apple has released the iOS 4.2 Gold Master (pre-final developer build) to the members of Apple developer program, The Gold Master or GM version is supposed to be shipped "as it is" to the public if no major issue is found - these special beta builds can only be used if you have your iDevice UDID registered with a developer account.
- New Volume, Backlight and AirPlay controls on the "Multitasking Bar".
- YouTube app gets AirPlay enabled - now sound can be streamed to AirPlay connected devices.
- Ability to create an Apple ID directly from the iOS settings page.
- More Restrictions can now be configured.
- Various bug fixes and other improvements.
iOS 4.2 GM IPSW file downloads are readily available on torrent portals and file-hosters but would need your device UUID registered with an valid Apple Developer Account to work, many developers sell these "spots" on forums enabling you to make use of these BETA iOS build son your iDevices.