If you have a gadget that's popular enough that you can more or less corner the market on key components, you end up with a pretty nice advantage:
In order to achieve its internal goal of shipping 40 million iPad products in 2011, Apple has occupied close to 60% of the global touch panel capacity causing tight supply among Apple's competitors, according to sources from upstream component makers.
There is a downside to that though. With their moves in the subscription space creating some anger amongst publishers, that number might embolden someone to push for anti-trust action. I've always been skeptical of that kind of thing, but I think Apple needs to keep it in mind as a real risk.