The way I see it and often explain it to people without having to go into great detail is to just list the factors involved in house prices and see what they indicate.

1) Economy – We are in VERY poor shape
2) Unemployment – Going higher based on every account
3) Inventory – Near record levels
4) Interest rates – getting worse
5) Foreclosures – getting much worse

Every single factor here points to downward pressure on home prices. When several of these turn around (and it will NOT happen overnight) then it could be a good time to jump into the market.