Many years ago when i first used an IBM PC (windows 3.1) one of my favourite past time is to download shareware app and playing with it. That was one of the reason that gets me hook up with software development, albeit i go into the engineering app direction for my career. Now, mobile app has recreated that excitement i once have with the infant PC. The PC eventually went all the way up with the internet age and has developed tremendously. Will the mobile phone industry and the app has the same direction going forward? My first PC is a Pentium 133 MHz with 2.1 GB Quantum Fireball IDE harddisk and today my laptop is at > 2GHz, duo core, with a 2 GB memory (now talk about with memory size matching my first pc entire hard disk space).
My first phone (Nokia 3310) is incapable of running current generation mobile app, although it does run the SNAKE game and i am not reallly sure what microcontroller it has inside, and now i have Nokia phone with ARM and ARM Cortex (with DSP), and even boast a graphics processor, and the processor speed is 670MHz (way faster than my first PC).
I never have the chance to go into consumer app development on PC platform, as engineering app is pretty much my entire programming life. Mobile app has really bring back the opportunity for me to dwelve into it. To add to the good news, there are plenty of useful resources online at Forum Nokia.
As a starter on mobile app development, particularly starting at UI standpoint, take a look at Design Process in a Nutshell, which is available at http://library.forum.nokia.com/topic/Design_and_User_Experience_Library/GUID-785FFE94-D4D9-48C9-82EE-8F20F19E0AF6.html