Sorry, but I can't believe the incredible amount of stupid comments posted here on this article. Jobs basically announces he's not dying and Apple's shares jump 4%. Apple isn't a one man operation and Wall Street knows that. It's probably safe to assume that every single innovation that's come out of Apple in the past 11 years hasn't been dumped straight from Steve's brain either.
Steve's marketing genius and patient leadership are the real value he provides to Apple, and losing his leadership is what makes investors nervous. As some suggest, Apple pulling the Stevenote from MacWorld is an attempt to address the former, but without a plan to address the latter, Wall Street will still freak out at the possibility of Apple losing Jobs.
In a world where IT companies are constantly diversifying their offerings, rushing products to market, and generally playing a bizarre game of throw 50 products at the market and see which ones stick, Apple is playing its cards close to its chest - and has been successfully since Job's return. It's not chasing emerging markets (Netbooks), it's not trying to get into online advertising (Microsoft) and hell it's not even doing things that outsiders think it should be doing to expand its business. Apple's stock value is based on the perception that is has a master plan. This is what makes Apple unique. And this is the value of Steve Jobs.
It's a naive, domestic operating system without any breeding, but I think you'll be amused by its presumption.