Doesn't look like we're there yet, according to the number crunchers at Zillow. As shown in the purple line in the graph below, housing prices are continuing to fall at a dramatic rate, and indeed are doing so at an ever faster rate, as depicted by the orange line (e.g. the second derivative is still negative):
At this point, a third of all mortgages are under water, which means that 1 in 5 of all homes in the U.S. are underwater. If you look at housing prices relative to headline inflation over the last thirty years, we're still way overvalued:
Now think about what this means for the holders of all the securities backed by these mortgages (e.g. the banks)... then think of what that means for the real economy.