Similar to the Free Weekends, Guest Passes and the features included in this Winter Update are further examples of the advanced services and functionality offered via Steam that define it as a pioneering service, reaching far beyond traditional downloaders.
Here's a look at some of the key features to be rolled out to the millions of Steam users in this Winter Update:
Guest Passes allow owners of certain Steam games (purchased either via Steam or at retail) to let their friends play games for free, for a limited time trial. The first game to take advantage of this new feature will be Day of Defeat: Source.
Background Client Updates
Since the Steam client was first released, it has always kept itself up to date -- but now it'll do so without making you wait during startup. Instead, it will acquire new updates in the background and then (once they're downloaded) ask if you'd like to restart and apply them. Steam will also let you know what's new whenever a new update is ready to apply.
New User Interface
Steam's got a new coat of paint. We've stripped away all the non-essentials and created a new streamlined appearance, available in five different colors.
Steam's catalog of games has grown quite a bit over the past year or so. The new Favorites feature in the My Games tab of Steam allows for quick access to your favorite Steam games and additional functionality for personalizing your Steam library of content.