Kotlin was being used in Android by Android Developers unofficially using libraries like ANKO. Yesterday, Kotlin was introduced as a second officially supported Android programming language in Google I/O.
Here are some links and resources to presentations and tools which I found useful for getting started with Kotlin for Android.
Here is an introduction presented by Wojtek Kaliciński which gives you a better perspective about how to use Kotlin in Android Studio 3.0:
Android Tool Time: Getting Started with Kotlin
I also found this presentation from Hadi Hariri in CERN a good resource to get up and running with Kotlin in about 45 minutes, I really encourage you to watch it.
Kotlin – Ready for production by Hadi Hariri
And finally download the new version of Android Studio 3.0 Canary from the official preview website.
Android Studio Preview Download
I hope these resources help jumpstart your next Android project using Kotlin and improve your productivity in Android Development.