HTC pushed the Android 4.3 kernel and framework code earlier today, and the update just started showing up for both Google Play Edition devices. Now Samsung is getting in on the whole open source thing. Yes, it has posted the new kernel source files for its Google Play Edition phone.
The MR1 version is Android 4.3, and it clocks in at 206MB. Developer types should feel free to download and tinker. Grab it at the link below, but be aware Samsung's servers are on the slow side.