I agree with the opinions here. As a few of you have pointed out, many people are moving in with family and friends and as Brian said, some are leaving the area completely.
With that said, some (or a lot) of this is local. When people move out of one area they are obviously moving into another. As investors, we need to ascertain where that location is. Real estate, as we all know, is very local. Each local market runs its own cycle and each market is in different stages of that cycle at different times. While one location is severly hurting, another may be an emerging market where economic development is occuring, jobs are moving into the area (well, ok, this one's a bit of a joke right now), or people are moving there to take advantage of lower costs relative to other cities.
Like Mike stated, the tricky part is figuring out how events in the macroeconomic environment will affect our local markets (and even more difficult, the timing of these effects).
In closing, this is still a time to invest. I'm seeing a lot of great prices out there. Will the prices go even lower? Sure. But that doesn't mean they still aren't steals for a 10-15 year investment horizon. I'm a buyer.