Valve has already confirmed that they are actively working on a Steam client for Linux platform.
They are now inviting applications from interested Linux users through a survey named “Valve Linux Steam Client Beta Application”.
The company said:
Over the next few days, we will be processing the responses. Shortly afterwards, we will notify selected participants individually and kick off the limited beta.
Valve is not only launching a Linux client of Steam but they are also developing Linux editions of their popular games.