We're developing for it (as well as the rest of android and ios) and as far as I'm aware there's no special coding that has to be done other than the standard controller support to get it working on shield. It works just like any other android device that hooks to the play store albeit not as good without the controller…
I believe any 600 series card or newer can stream to the Nvidia shield through local wifi. Nice if you share rooms with people and can't play at your desk for any reason. Being able to play Android games is a bit redundent for most people with a smart phone, but kinda awesome if you already got some high end android games…