When the property bubble in Hong Kong burst, average Hong Kong apartment prices fell about 66% according to the official index between the peak (October 1997) and trough (July 2003) (for a graph, click here). The result of this was a long-term recession, deflation, and general economic malaise.
The United States is now epxeriencing a bursting property bubble. Few expect the correction to be as large as that experienced in Hong Kong, and to date prices have only dropped a few percentage points. But this may be just the beginning- see this news clip on YouTube for more. Expect a similar consequence for the US economy as HK's.
Thanks to Calculated Risk for the link.