Now, personally, I agree all this is irrational exuberance. But, I don't see it as a huge problem. As far as that goes, I'm not sure the first .com bubble and crash was really a bad thing for the industry. (the first .com bubble and crash were
very good for me personally, even though they were clearly mis-allocations of capital from a societal viewpoint.) Huge amounts of infrastructure (software and hardware) was constructed. Many new Engineers were attracted and trained. (of course, it was bad for those who didn't make the cut during the crash, but it was probably quite good for the industry as a whole)
Sure, some speculators are going to get soaked... but that's what happens when a speculator is wrong. I don't see that as a bad thing. Capitalism is based on this idea that speculation is fine; it's just that if you are wrong too many times, well, you can't speculate any more because you don't have any more money.
I know that I personally am rather jealous of Zuckburg. I don't feel he "deserves" to be that rich, but eh, that's not mine to decide. He certainly has more of a claim to that money than the CEO of Enron or GM, you know?
Sure, we're mis-allocating a lot of capital. But you know? the capital is coming from rich speculators, I believe, as it's so goddamn difficult to IPO these days, and a bunch of it is being used to prop up Engineer salaries, so while I recognize that it's an inefficient mis-allocation of capital, it's a wealth redistribution over which I certainly won't shed any tears.
Personally, I think this wealth redistribution from speculators to Engineers will continue this trend towards more realistic and more efficient Internet businesses, as more of the speculators are replaced by Engineers who made it big in the last boom. This is, after all, how we got Paul Graham and Ycombinator.