Previously, the App Launcher was only available to users of the developer preview of Chrome. It's now stable enough that Google has released it for all Windows users. Mac and Linux users will have to wait a bit longer but Google is working on bringing the Chrome App Launcher to the platforms.
Using the App Launcher is simple; just install the extension and you'll notice a new icon in your taskbar. Click on it and it'll give you pages of apps you have installed for Chrome. There's a search bar up top if you want quick access to an app. There's also a settings menu where you can log into your Google account, change advanced sync settings, and switch user profiles.
To try the Chrome App Launcher yourself, hit up the download link below.