The popular email app Sparrow was recently acquired by Google for a tidy sum, and pretty much immediately mothballed. This has resulted in a firestorm of criticism leveled at both Google and the Sparrow developers. "Why can't independent developers stay independent?" is a common refrain. "Why must they always sell out like this?"
Two independent app developers have done some in-depth analysis of the App Store economy. App Cubby's David Barnard, developer of Launch Center Pro,
