Now that we have seen a full bore, global panic and crash, it might be worth sorting out how many bubbles there have been, and which of the three patterns identified by Minsky and Kindleberger (and first formally modeled by me, dating back to 1991) each has followed.
So, the first and most fundamental has been the housing bubble. This seems to have followed the pattern of gradually up and then gradually down, with no crash. The peak was end of 2005, and if one believes the various Shiller indexes, it still has a good 10-40% to go or so. Of course real estate bubbles rarely crash, unless they are for vacant land as in Florida in the 1920s, as people will generally not dump their own homes in a panic.
The next was the derivatives bubble. Whereas the housing bubble fairly clearly started around 2000 or 2001 after the tech stock crash, the beginning of the derivatives bubble is shrouded in mist, still much about it is not well known. However, it looks to have followed the peak followed by a period of financial distress and then a crash pattern, the most common pattern for major bubbles. The peak would appear to have been August, 2007, and the crash was the outright financial market panic on Sept. 17, 2008, after Lehman Brothers was allowed to fail and AIG nearly went under, with Treasury yields dropping to 0.06% at one point. This crash ended with the announcement of the bailout of AIG and that there would be a broader bailout, although clearly the credit and derivative markets have not really recovered from that crash.
Then there was the oil bubble, which looks more like the theoretically preferred one that goes up, peaks, and then pretty much crashes, which happened in July, although it has continued to sink since, and very rapidly in recent days.
Finally there is the behavior of the stock markets. While there was a bubble in US stocks in the 1990s, the more recent behavior has not been particularly bubbly. The sharp crash of the last few days has been a negative bubble, an epiphenomenon emanating from the crashes of the derivatives and credit markets, collateral damage, although quite serious, and threatening to take down the real economy as well (bankruptcy for General Motors anybody?).