1) iOS (Apple)
2) Android ( Google )
3) BlackBerryOS ( RIM )
4) Windows Phone 7 ( Microsoft )
5) WebOS ( HP formerly Palm )
The first three mobile platforms each have close to a third of the market share. Yet their ‘native’ application platforms are all different. All of these devices have modern HTML5 browsers.
As a Mobile App Developer, you want to target as many different platforms and customers as you possibly can. At the same time, your app needs to look GOOD and it needs to be consistent across platforms. Finding the talent to target all these native platforms would be expensive.
10) Windows 8