It matters whether we think it is a bubble, because the day there is a consensus that it is, it will have popped. And then we will be in the post-bubble world. So what? A few rich investors will lose billions. If they're smart they're already hedging. They might lose billions after making more billions.
The people to worry about are the entrepreneurs and their employees, because this time there are many more of them (despite this misleading chart in the NYT today). In this bubble there's a long tail of individuals starting companies. And they're almost all very young, and probably don't have a cushion to ride on through the inevitable downturn.
The last tech bubble burst really hit the people hard. And this time, because it's had more time to inflate and because it's built around user generated content, the failures will have a wider impact, again on people, and on the web.
The winners are going to be people who have cash-generating businesses. And users who, instead of accepting the illusion of free web services, didn't cut corners and are using servers they control. Because as the companies caught in the downturn look for ways to monetize, their silos will have fewer openings and they'll be higher up, further out of reach. Pity the businesses that built on the assumption that Facebook and Twitter would always host their presence on favorable terms. Those are variables whose value will be different after the bubble pops.