"depression scare is kinda back", "market is slightly overvalued" and there's "substantial probability of a double dip" for the economy. He also warned about the risk of Japan-style deflation and a double dip in housing.
Shiller's meaning of a double dip: "Situation in which unemployment doesn't return to normal between recessions".
Oh by the way, Barry Ritholz (on Tech Ticker) sees another 10% decline in housing. Gary Shilling and Meredith Whitney feel the same way.