While people will want to dismiss this because it's based in several devices, prior to the release of the new iPhone, and because it's still restricted to AT&T - all valid facts - the important thing to notice here is trend. Android devices have been gaining market pretty solidly lately; first the AdMob ad pushing statistics, now unit sales... this seems to be one from many more that will come.
Apple has no reason to be afraid, I'm pretty sure, as they are probably happy in having just a slice of the market and still being super lucrative (same position they play in the desktop business). But for app developers, this is a pretty strong hit of future market changes.