Test your app on all Android versions before release to Market, or, if you're too lazy, just on:
- 1.5 (older one, lacks support of some classes that 2.x does)
- 2.1 (most modern devices)
- 2.2 (most current, not much devices for now, has some internal rendering changes)
Earlier than 1.5 are hard to find, so can be safely ignored.
android-remote-stacktrace is also very useful thing