We created the iOS version and another company, Mobage ported it to Android for us. About a year ago they decided to remove our apps and several other apps from their platform. Only our apps that were previously ported by Mobage (Tiny Tower, Pocket Planes and Pocket Frogs) are affected. All others will remain on the Google Play store.
Tiny Tower was recently re-released on Android but the Mobage version data is non-transferrable.
We have no current plans to re-port the iOS versions of Pocket Planes and Pocket Frogs to Android though future sequels or major updates could possibly support Android.