>"Many economists argue that house prices have risen too far too fast in many markets, forming a bubble that could rapidly collapse and trigger an economic downturn"
I've heard this from various corners as well, and it utterly amazes me that there are people who would actually try to claim that with a straight face. There certainly was plenty of warning of the housing bubble both in the mainstream press and elsewhere. Here are just a couple of examples:
The Economist called it "the biggest bubble in history" in 2005:
http://www.economist.com/node/4079027
And here is a blog which goes back to 2004 dedicated to discussing the housing bubble:
http://thehousingbubble.blogspot.com (original site)
http://thehousingbubbleblog.com (post-move site)
http://en.wikipedia.org/wiki/United_States_housing_bubble#Id...
In short, it's quite obvious that plenty of people "saw it coming", and anyone trying to claim otherwise is just desperately playing the CYA game.