A Brand New Steam

Game publisher and digital distribution giant Valve has just pulled the curtain on a completely redesigned version of Steam. Available as an opt-in beta, the updated client is said to bring "hundreds of changes" aimed at improving the user interface, performance and functionality of the digital download service.

Some of the most notable improvements include an expanded Friends List to let players keep closer tabs on what their contacts are playing, a new in-game overlay design with more context sensitive information, redesigned Steam store, and several other UI changes that should improve the discoverability of features and better expose all the information related to games in your library. They've also swapped out the Internet Explorer web browser rendering engine with the faster and more stable WebKit.

The new Steam UI is here, which enhances the way you already buy and play games, adding more info about the things that matter — getting games, playing them with friends, and staying current in the gaming world.....

A full rundown of the new features can be found at the Steam website.
Just let your steam update and then enjoy the whole new steam.