Valve has updated their Steam mobile app for both Google Android and Apple iOS platforms.
It is now open to everyone. It has been limited to a small number of beta testers until now.
The app has features like:
Staying in touch with your Steam friends on the move.
Chatting capabilities with your Steam friends on the move.
Ability to check out the Steam store on the move.
Ability to keep an eye on latest discounts on the Steam store.