There are far more houses for sale then there are qualified buyers. Some combination of chicanery and stupidity on the part of mortgage brokers/banks/FHA managed to temporarily 'juice' the pool of 'qualified buyers', largely by using the same tactics that credit card companies have: Give everyone credit and charge a savage interest rate.
For credit card companies, it was a great strategy, especially thanks to recent changes in bankruptcy law (2k8?) mandating that credit card debt was not erased by bankruptcy. For mortgage companies, that has worked less well: Home-owners have increasingly decided to walk away from their huge debts.
To use an analogy, the Federal house credit solidified house prices today, by shot-gunning almost ready home buyers into todays housing pool. However, it's a case of diminishing marginal returns. Everyone who can reasonably afford* to buy a house has bought one.
In combination with the next surge of defaults, expect things to get nasty.
*Stable employment, good credit, cash savings for down payment, unlikely to move...