I think Apple's real secret weapon is Steve Jobs. Apple has built a following on stylish, mostly well made products, and great marketing. There's no reason other companies can't do the same, but for it to really work, you need a strong visionary leader at the helm. Love him or hate him, Steve Jobs is that guy. I'll never forget how when Apple bought NeXt and brought Jobs back, he swiftly took over the whole company and turned it around.
That's why the shareholders are so worried about what happens to Apple after Jobs is gone. In a lot of ways, Steve Jobs is Apple. Who is HP? Who is Motorola? I have no idea, and neither do consumers.