The greater use of "custom silicon" along the lines of the A4 processor is a greater indication of Apple's future of doing everything in-house. Having complete "artistic" control over future projects can be exciting, but at the same time can create havoc in a consumer market.
For instance, building your own processor has great benefits for tailoring the final product, but it does mean having and retaining the engineers and brain trust to continue product development and support, as well as getting things to market on time. Trailblazing means you have to bring everything and everyone to the expedition.