Openness is one of the main advantages Android has over other platforms like iOS. With this in mind, Android smartphone manufacturers would usually release the open source kernel source code for their smartphone releases, which modders and tweakers can use to make their own builds.
With the release of the Samsung Galaxy Note 2 on various carriers, such as T-Mobile and Sprint, Samsung has also released open source kernel files for these models. As a bonus, Sammy has also released the source or the AT&T Galaxy Rugby Pro. These are available for download via opensource.samsung.com. You can get the kernel source separately for the Sprint, T-Mobile and US Cellular versions, and also for the AT&T Galaxy Rugby Pro.
These open source kernel releases are quite the resource for advanced Android users out there. But the more interesting issue at this point is whether it will still be legal to root your phone or to install a custom ROM. The U.S. Library of Congress has released new guidelines on the legality of rooting/jailbreaking and phone unlocking, which makes for good reference to anyone into such tweaks. Does this source code release give implicit approval to tweak and install custom ROMs?