Yes, this chart is indeed PE-10, which is the average PE over the past 10 years.
The current P/E ratio of the SP500 is around 16, and not 22.8 as the PE-10 shows.
If one wants cheaper stocks, there is emerging-market stock, with PE of 12 for an index (FTSE perhaps, I forgot). Also, a PIMCO money manager recently pointed out that emerging-market bonds also have better yields than US ones, yet emerging countries are not laden with debt like developed countries are.
Moreover, I find it interesting that Burton Malkiel, the author of the well-known book "A Random Walk Down Wall Street" and a buddy of John Bogle, also noted in more than one recent article or interview that emerging stocks and bonds should be good buys. As a proponent of the Efficient Market Hypothesis, albeit only in the weak sense, meaning that in the short-term the market may act irrationally (of course we know this), his stance is noteworthy.