[adamauckland]

It's actually not that hard. iCloud and GrooveShark are quite graphic-heavy which gives them that extra edge. Frontend technologies are pushing forward at an incredible rate.

Have you played with Sencha Touch or Google's Angular JS or Ember or Backbone?

These are all great starting points and will teach you a lot about how to structure your code, but for anything large like iCloud, you're going to probably need to write your own libraries because nobody else is doing exactly what you want.

Get good at using jQuery to animate stuff, then re-work your UI using CSS3 transitions (because jQuery suffers performance issues on mobile).

Design for mobile first and scale upwards; by design I don't mean PSDs I mean open an HTML document and just start chopping it up.