I think part of the loyalty numbers for iPhone users is the substantial investment they make in other Apple hardware, software, and App Store apps. Unfortunately, I don't have any hard data to back this up, but I imagine a large percentage of iPhone users have at least one other piece of Apple hardware, such as a Mac, iPad, iPod Touch, etc., that works seamlessly alongside the iPhone and iTunes. That makes it tougher to break away from the iPhone. My coworker is one such example. He has an iPhone, a Macbook, and a Mac Mini. He loves the fact that iTunes ties them all together, and wouldn't get a different phone because of it.

Android doesn't have that kind of integration, simply because there isn't that tight integration. For example, my girlfriend and I both have Android phones, but everything else we have is Microsoft (2 laptops on XP and Vista, a media center PC and a Viliv S5 tablet on Windows 7, and an XBox 360). If Google could get all of those other devices dependent on Google software like Apple does with iTunes, they'd have a shot at keeping people loyal.

You'll also notice that Microsoft missed a big opportunity here. In addition to all of that Microsoft hardware, we used to both have Windows Mobile phones, but there was nothing to tie them all together like iTunes. I would have thought something like XBox Live Marketplace could have worked (e.g. as a central place to buy content for all my devices, share contacts and data, etc.), but Microsoft never executed. Maybe with Windows Phone 7 they will...