I see on the Android SDK pages, it mentions some screen resolutions to expect on Android platforms:
Small screen
QVGA (240x320), 2.6"-3.0" diagonal
Normal screen
WQVGA (240x400), 3.2"-3.5" diagonal
FWQVGA (240x432), 3.5"-3.8" diagonal
HVGA (320x480), 3.0"-3.5" diagonal
WVGA (480x800), 3.3"-4.0" diagonal
FWVGA (480x854), 3.5"-4.0" diagonal
Large screen
WVGA (480x800), 4.8"-5.5" diagonal
FWVGA (480x854), 5.0"-5.8" diagonal
Obviously, testing an app you want to sell on all these resolutions is going to be a pain. Is there any data on what percent of android phones being used use the above resolutions? My hope is that there's only really 3 or so popular resolutions...