As you can see, "fair value" (the green line) is fair value because the S&P 500 has historically spent about half the time below that level--often after spending many years above it. Given the cyclicality of this ratio, if we had to guess, we'd say the S&P 500 is in for a decade or two of below-average values, which argues against the idea that we're suddenly going to have a strong, sustainable valuation recovery.
More likely, the bear market that began in 2000 (after an 18 year bull market) will likely continue for another decade or so, during which stocks will occasionally become truly cheap--as they almost did a week ago, when the S&P 500 hit 750.
"No investment bank owned by its employees would have levered itself 35 to 1 or bought and held $50 billion in mezzanine C.D.O.'s. I doubt any partnership would have sought to game the rating agencies or leap into bed with loan sharks or even allow mezzanine C.D.O.'s to be sold to its customers. The hoped-for short-term gain would not have justified the long-term hit."

The Glitch Mob live @ Mezzanine, San Franicsco October 2008
Video by Dugan O'neal and Bemo
Cast: the glitch mob
The world first non official short movie shot with the Canon EOS 5D MarkII
1 cameraman with Canon 5D MarkII - 3 days in Tokyo
1 video editor with MacBook Pro - 2 days in France
More informations on:
utsuru.fr (english & french)
lejapon.fr/blog/