- Tossing most of your current UI code
- Being way more careful about object/memory use
- Relying on your Objective-C & Cocoa skills for visual element design since NIBs are non-esistent
- Learning a whole new way to get input from the user and info to the user
He goes into a decent amount of detail (as much as he probably can given the lack of a public API release) and leaves the reader with a good sense of what it will be like in the brave, new iWorld.