iOS 4.2 GM Released To Developers. Public Release Soon!
Apple is now allowing access to Xcode and iOS 4.2 SDK GM Seed, build 10M2423, and firmware build 8C134. Registered developers can head over to the Apple iPhone Dev Center to download. The final version of iOS 4.2 is expected to be available sometime this November.
WARNING: If you jailbreak/unlock your iPhone, DO NOT UPDATE right away. iOS 4.2 cannot be jailbroken properly yet, and the baseband that comes with it cannot be unlocked yet. Just be patient, and wait for the tools to be updated. The iPhone Dev Team will have an update for us, shortly after iOS 4.2 is public, and then we’ll know where we stand.
As always, make sure you back up your iDevices SHSH blobs! Follow the guide below using TinyUmbrella: