You can now manage your Steam library remotely via a web browser or Steam's mobile app. In other words, you can now purchase a game remotely, and have it download automatically to any of your computers. You can also reinstall any of your titles remotely... but I doubt that many people will use that feature.
"To kick off a remote download, simply visit your Games list on the Steam Community site, which can be accessed from your own profile using a web browser or the Steam mobile app on iOS or Android. If logged into the latest update of the Steam client on a PC or Mac, there you’ll see which games are currently installed, and have the ability to install others from your library. Or, seamlessly complete your online purchase with remote installation: When a remote session is detected, the Steam store will ask whether you'd like to download your new purchases immediately," Steam announced.