A few weeks ago, Dianne Hackborn wrote about the new Fragments API, a mechanism that makes it easier for applications to scale across a variety of screen sizes.
The new Fragments API, which is part of Honeycomb, does not help developers whose applications target earlier versions of Android.
Today Google have released a static library that exposes the same Fragments API (as well as the new LoaderManager and a few other classes) so that applications compatible with Android 1.6 or later can use fragments to create tablet-compatible user interfaces. it’s called “Android Compatibility package”.
This library is available through the SDK Updater.
To install the in your existent Eclipse with ndroid SDK, click Window Android SDK and AVD Manager, select Available packages on the left.