We obviously live in an internet era.
Many recent graduates are forming startups hoping to reap the rewards like Yahoo (in the oldest days) Google (in the old days) and Facebook/Twitter in the present.
These are popular services, no doubt about it, and the press just can't stop talking about them. Valuations and IPOs are completely without realism. It's like saying that the most successful company in world commerce is the Yellow Pages.
These silly valuations come from investors fear of missing out on the next big IPO.
But are we forgetting something ? All these billion dollar-valuation companies are all single dimensional. They are all just web apps. Software really. So while their services may be innovative in their offerings, they are really just very big software houses.
I see complaints that the US is losing it's edge in innovation and R&D. No surprise really. While US is busy building web apps, China and Korea and the rest of the world are doing R&D in flat panels, lasers, semiconductor materials, acoustics, vehicle safety, and green energy. Multi-dimensional.