Earlier this week Apple released the Gold Master version of iOS 4.2 and the corresponding SDK to developers, bringing the current version of both to 4.2 GM (builds 8C134 and 10M2423 respectively).
So far those people that have tried the new updates are telling us of more stability, as well as several changes/additions, these are as follows:
The GM build is typically the final shipping build that will eventually reach customers.
Apple originally detailed the upcoming features of iOS 4.2 back in September. The focus of the update will be to bring the iPad up to speed with other iOS 4.x features such as multitasking and folders.
Back in September Steve Jobs promised a release within November, so we are hoping to see an update soon.