Hey, here's an update exclusive to the Android version: The APK file is now signed.
Yep, that's the update. Other than that, it's basically the same as 2.1 version, so you don't have to update it if you don't want to.
Well, that's all, see ya.
-TSHM

P.S. In case you wanted to update to 2.2 despite it literally being identical to 2.1, you have to uninstall the game and reinstall it, otherwise the game won't be able to update it.