Last week, Apple released the iOS 4.2 second GM build to the developers as some bugs were yet to be solved. There were some compatibility issues for the first build with the iPad Wi-Fi. Now they have released the iOS 4.2.1 GM build for iPhone, iPod Touch and the iPad and is available to download. But remember, this is only for the developers.
Download iOS 4.2.1 for iPhone, iPod Touch or iPad from here.
We can hope that Apple makes the iOS 4.2 final public soon. Stay tuned to Tips Needed for more updates!