(jeffcl612)Areas like Las Vegas, Phoenix, and Miami — all hit pretty hard by the collapse of the last housing bubble — are now seeing home prices rise at rates above the national average. But rather than this being an indicator that these areas are finally recovering, some worry that it’s just a lot of hot air being pumped into another bubble by Wall Street investors. The Washington Post reports on the huge amounts of money that institutional investors are putting into single-family homes in some areas hit the hardest in recent years.