I don't have access to the right kind of data to decide whether there is a housing bubble in the US, though a lot of people are writing about it.
In the Phoenix / Scottsdale area, housing values have really starting going up, up, up in the last 18 months, though whether this is just a catch-up to other desirable metropolitan areas (Phoenix real estate has been pretty sluggish for years, and way cheaper than other resort-type destinations) or a true bubble, I can't tell. Certainly speculation activity is way up, with a lot of homes being bought and renovated by investors, but again, I could argue that Scottsdale was behind other suburban markets in the whole tear-down thing.
So, to date, I have been unconvinced about the housing bubble, at least as it applied to our community. After all, demographics over the next 20-30 years are only going to support Scottsdale area real estate.
However, over the weekend I had a disturbing experience: At a social function, I heard a dentist enthusiastically telling a doctor that he needs to be buying condos and raw land. The dentist claimed to be flipping raw land parcels for 100% in less than 6 months.
For those who don't know, this is a big flashing red light. When doctors and dentists start trying to sell you on a particular type of investment, run away like they have the plague. At Harvard Business School, I had a great investment management class with a professor who has schooled many of the best in the business. If an investment we were analyzing turned out to be a real dog, he would ask us "who do you sell this to?" and the class would shout "doctors!" And, if the investment was really, really bad, to the point of being insane, the class would instead shout "dentists!" Marginal Revolution has another potential bubble indicator. Angry Bear has a lengthy analysis.
Postscript: By the way, just so you doctors and dentists won't feel like I am picking on you, we small business owners are considered to be almost as bad, which is I why I get so many boiler room calls.
Update: OK, in one of those great moments in timing, my wife just called me to say that one of the moms at school was trying to get other moms to invest with her in some condos, and should we join in? Eeeek!