Mobile application developments are highly linked with hardware platforms, new technology integration and user types. As a programming language, you could use mainly .net compact framework (really easy to start a 'helloworld' of c# in Visual studio), J2ME. But deployment, testing or running in the device needs some steps, tools. Because you develop it in the PC. So as language, You will see variety of devices like PDA, smart phone, iPhone, rugged handheld, with different platforms like windows mobile, CE, palm OS.