After testing it out with select few users, Steam In-Home Streaming went into Open Beta today for further testing.
Basically, what this feature does is that it lets you stream games between two computers over the same network. Obviously, you would need a very good-quality Internet connection to be able to utilize this feature flawlessly.
In essence, In-Home Streaming is not very different from the Remote Play feature found in PS Vita or the ability to play Windows games from Nvidia Shield but the plus side to this is that you do not need two very expensive gaming equipment.
Only the main computer should be able to run the game you are interested in playing, meanwhile the other machine can be a very weak system running a totally different OS.
Setting up this feature on your machines is really easy. All you need is the Steam Beta Client which can be downloaded by changing the client type in your Steam settings menu.
Make sure both computers are connected to the same network, login with your steam account on both machines, and you should see the ability to Stream games (instead of the usual Play).
Being in early stages, this service may not be the best one out there in terms of sharpness and crisp visual quality or the general lagginess of gameplay, but the fact that the client can even run gameplay at 4K resolution speaks volumes about the bright future of this free service.