Valve will release really soon a "Steam Link" app for the two major mobile OS.
Steam In-Home Streaming have been a reality for a long time and it works pretty well if your local network is up to the task.
Coincidentally NVIDIA with the Shield Portable together with Nvidia Gamestream software made possible to play your PC games on a compact and portable device, which become relatively popular.
Other alternatives exist, the more effective one is called Moonlight and it is an open source client for NVIDIA Gamestream for different OS and hardware, yet it isnot as good as the native NVIDIA client.
With the launch of the Steam Link app in May 21st, Valve will make all the "bathroom gamers" happy, yet we hope the software will be polished from the launch day, given that the current Steam mobile App is not that great or polished.