is still a bit tautological --- it is only a bubble if it bursts

Until it bursts, it's a speculative bubble. Just as two quarters of negative growth isn't a recession until it is. Or, accumulated rain isn't a flood until it reaches some depth or strong winds aren't a hurricane until they reach a certain speed.

Sometimes, unprecedented growth isn't a sign of impending catastrophe. For example, a Dow basis of 1000 seemed wildly optimistic in 1980 and anything under 10,000 is now disaster.

You're argument makes a bit more sense now that we are inserting 'bursting' into the sentence, but it is still a bit tautological --- it is only a bubble if it bursts and not is parabolic growth rates typical of a mature asset category and are deviations of three, four and five standard deviations from previous trend relationships with otherwise reliable proxies explainable by anything other than 'new paradigm' talk?

Maybe you forgot to type 'bursting' of the bubble in your argument, but the bubble was co-occurring with generationally low interest rates and massive amounts of media cheerleading

True enough. Still, it's only a "bubble" if it bursts; otherwise, it's merely "growth." Look at some of the "Related Articles" above -- there were WaPo and NYT gloom and doom stories two or three years ago on this.

UPDATE: OTB's first Housing Bubble post was in April 2004.

Try finding a prominent, non-Krugman, non-Dean Baker columnist who had an audience of at least 10,000 eyeballs a week in 2003/2004 saying that there was an imminent housing bubble. I don't think you are going to find that individual. You'll find a couple of bloggers who were saying 'something funky is going on here' in 2003/2004 but Calculated Risk, the biggest housing blogger today is still not widely read except for info and finance junkies.

Maybe you forgot to type 'bursting' of the bubble in your argument, but the bubble was co-occurring with generationally low interest rates and massive amounts of media cheerleading, and every idiot can be a multi-millionaire house flipper seminar selling a 'new paradigm' of 'housing only goes up'

The supply of greater fools ran out and that is what caused the bubble to burst.

Between 1989 and 2006, the median inflation-adjusted price of a Seattle house rose from $221,000 to $447,800. Fully $200,000 of that increase was the result of land-use regulations, says Theo Eicher — twice the financial impact that regulation has had on other major U.S. cities.