Today, Firebase is announcing support for Android applications. Firebase lets you seamlessly add a realtime data backend to your Android applications. You don't need a server, and you don't need to poll for updates, Firebase will push them to you.
Not only that, but Firebase also supports the same functionality on iOS and on the web, so it's the perfect tool if you're building for more than one platform.
Check out the blog post and screencast for more details: https://www.firebase.com/blog/2013-07-02-firebase-java-android-sdk.html