You can target specific hardware features (keypad, touchscreen, etc.) in the package manifest. The Android Market uses this to filter out apps that can't be run

You can target specific hardware features (keypad, touchscreen, etc.) in the package manifest. The Android Market uses this to filter out apps that can't be run on your phone. It's not a really a matter of 'least-common-denominator' design; it's a trade off between how wide of an audience you want to reach and how many features you want to use.