I saw that in the news and almost threw up
Seriously? I mean I know the iPhone is a great invention but to be worth more than oil companies like Exxon Mobile that are the backbone of our industrialized civilization? Wow...
I think that time has actually gone past, my friend. The world is no longer stuck in the Industrial Era. We are now (especially the Western countries and some Eastern countries like India) in a (financial) services orientated world. A very substantial amount of American GDP comes from the services sector, with the financial sector (Wall St., London, etc.) having a huge impact on world economies.
So in this financial services oriented economy, why wouldn't a company that makes an OS, computers, mobile gadgets like iPads, among other stuff be the most valuable company? It's very representative of what's been going on for the last 2 to 3 decades: the conversion of an economy based on oil and manufacturing to a services economy based on computers and $$.
Besides, with oil going to be scarcer and scarcer, and the renewed push for "green" technology, Exxon will lose some market cap value... just from a business standpoint. That really should be expected in the next few decades anyway...