Google is making its Nexus 5 launcher available for other Android-powered devices, with a few conditions. The Google Now Launcher was initially available with the Nexus 5 and then with other Nexus and Google Play Edition devices. Now, Android users with devices running on version 4.1 or higher will gain access to the launcher. You just have to make sure you are running the latest version of the Google Search app.
The launcher will change your homescreen to look identical to that of the Nexus 5 when it first launched. You will gain access to the “Ok, Google” voice command, new wallpapers, as well as the ability to see all your cards just by swiping to the right from your home screen.
Source: Ubergizmo