XBMC started life as a hack for the original Xbox game console, but it has since evolved into a much-beloved open source home theater system on a number of platforms. After months of release candidates and betas, XBMC 13.0 (codename Gotham) is ready to download on Android (and other stuff).
The new version brings a number of improvements, only some of which pertain directly to Android. The most relevant to our interests is the inclusion of hardware media decoding on ARM and x86 Android devices. That means you won't need to burn through your battery decoding media via software methods. The XBMC team also says performance has been improved on Android (and Raspberry Pi).
General updates in Gotham that you'll also see reflected on Android include improved UPnP, a better audio engine, and enhanced touchscreen gesture control. Check out the site for a detailed explanation of everything added in this version. XBMC is a standard APK, but it's not in Google Play. You'll have to grab it from the XBMC site and sideload it on your device. Just make sure you get the right version –ARM or x86.