This feature is come up with Android 4.2 JellyBean. Hope you got 4.2 update in your device. I can explore such features in Nexus 7.
Now, What exactly DayDream feature is about?
Daydream is an interactive screensaver mode that starts when a user’s device is docked or charging. In this mode, the system launches a daydream – a remote content service provided by an installed app – as the device screensaver.
A user can enable Daydream from the Settings -> Display -> DayDream and then choose the daydream to display.
Daydreams combine the best capabilities of live wallpapers and home screen widgets, but they are more powerful. They let you offer the any kind of content in a completely new context, with user interactions such as flipping through photos, playing audio or video, or jumping straight into your app with a single touch.
Because daydreams can start automatically when a device is charging or docked, they also give your app a great way to support new types of user experiences, such as leanback or exhibition mode, demo or kiosk mode, and “attract mode” – all without requiring special hardware.
Daydreams are similar to Activities and can do anything that Activity can do – from rendering a UI hierarchy (without using RemoteViews) to drawing directly using Canvas, OpenGL, SurfaceTexture, and more. They can play video and audio and they can even accept direct user interaction. However, daydreams are not Activities, so they don’t affect the backstack or appear in Recents and they cannot be launched directly from your app.
Implementing a daydream is straightforward and you can take advantage of UI components and resources that you’ve already created for other parts of your app. You can provide multiple daydreams in your app and you can offer distinct content and display settings for each.
Info courtesy: JellyBean | Android Developers