Are stocks expensive?

For some reason, an important graphic was left out of the online version of this story in today's Wall Street Journal and it seemed like a good idea to reproduce it here from the print edition in an attempt to better understand the questions that David Wessel asks about whether stocks are cheap or expensive today, on the one-year anniversary of the low last March and a full ten years after the Nasdaq reached its all-time high back in 2000.

Anyone looking closely at this chart from Yale economist Robert Shiller would say that, at this point, stocks are a bit pricey. In fact, what's remarkable about the data below is just how expensive shares were a year ago when people talked of generational lows in valuations. As it turns out, early-2009 was the only period since 1991 when stocks were below the long-run historical average when calculated as Shiller has done.
While some would surely argue that we've reached a permanently high plateau for valuations since the 1980s, higher prices may have much more to do with how radically different the financial world is today than it was in the century before the 1980s.

With seemingly no limit on how much money and credit can be created and pushed into the system to make all sorts of asset prices levitate, is it reasonable to think that we'll ever see a secular bear market bottom like the ones in 1982 and prior?