Usually a good indication of an actual bubble is that nobody believes it's a bubble. When you have the average man on the street thinking this is the new wave and we're all guaranteed to get rich off software companies, then it may be a bubble. Right now it seems like there's a healthy skepticism in the general public.
The economy has been so crappy that people are crossing their fingers and pretending a bubble doesn't exist even though deep down they know it does. After all, it can't get any worse, right? It's like people who have terminal cancer and are otherwise rational skeptics who decide to pursue alternative therapy. Hope, even false hope, is a powerful thing.
Because the economy is so crappy money is flowing into the one area which still has the (perceived) possibility of a significant positive return on investment.
Unfortunately, like markets tend to do, that's been raising the prices/valuations to levels at which few investors will be actually able to get market beating returns on investment.
If I'm right then this market is indeed experiencing an artificially high demand, but the dynamics make it more likely to simply have it dry up eventually rather than having it pop (like a bubble would.)
"A recent Bloomberg survey of Wall Street investors, analysts and traders who use the company’s financial data terminals found that the majority thought Internet and social media stocks were at or near unsustainable levels.
Roughly half said that the bubble was here or soon would be."
