Making an app that works on iPhone, Android and Windows Phone 7 is tricky. Each of the platforms is different from the others in many ways.
The most obvious thing about iPhone, Android and Windows Phone 7 that's different is the user interface, which is different on all platforms because all of the platforms want to stand out and entice the user into choosing that platform. There's even more going on under the hood. Each of the platforms not only has its own user interface components with matching patterns, there's also a whole host of other things that is different. Most of the differences however have to do with the way the devices were build. Android, iPhone and Windows Phone 7 all have access to telephony, GPS and internet, but all of them do it differently.<!--more-->