From RealTrends.com:  While an August report from Capital Economics states that housing values overall are undervalued by 20 percent, Zillow reports that many metro price-to-income ratios are still above their historic averages.  The current price-to-income ratio for the U.S. is 3.3 to 14 percent above the historical average, according to new research from Zillow.  The Seattle-based company’s chief economist Stan Humphries says “more often than not, home values will eventually come back in line with incomes, according to the historic norms of that market.”