The dotcom crash of 2001 is a spectre that haunts anyone who makes their living on the internet. Those who work around what’s often called Web 2.0 are particularly sensitive about it because if another online slump materializes, that’s where it will strike.

But what will be the harbinger of a Web 2.0 crash? According to Dave Winer, that grand oldish man of blogs, RSS and OPML outliners, it will be signalled by the busting of Google.

… today we got the first rumblings of the shock that will signal the end of the bubble. Google stock will crash. That’s how we’ll know.

When I realized this, I should have known, because I’ve been saying for almost a year that Web 2.0 is nothing more than an aftermarket for Google. Startups slicing little bits of Google’s P/E ratio, acting as sales reps for Google ads, and getting great multiples for the revenue they generate by fostering the creation of new UGC to place ads on. When Google crashes, that’s the end of that, no more wave to ride, no more aftermarket, Bubble Burst 2.0. And the flip of this is also true — as long as Google’s stock stays up, no bubble burst.

Currently Google stock is riding high around $500 and forecast to go to $600 within a year. But stranger things have happened.

Now we hear this : “Google shares, which topped a milestone price of $500 a share last week, are overvalued and poised to fall, says Barron’s financial newspaper.

New.com reports : “Barron’s said Google is overvalued because it trades at 37 times next year’s expected earnings and because its growth rate is slowing.”

Is the bell already tolling for Google and Web 2.0?