Via Jon Cohn, a group of scholars at the Rockefeller Center, led by Jacob Hacker, have created a new measure called the Economic Security Index to complement the more traditional measures of poverty. Basically, it measures the number of people who have experienced a major loss in income (25% or more) — either due to a decline in income or large out-of-pocket medical expenses or both — and who lack adequate financial wealth to buffer the drop. By their projection, the number of Americans in this category is now over 20%, far higher than in any previous recession.
If you go to the ESI site, you can also play around with the index. How many people have lost a third of their income? Half? How are high school dropouts doing? How are different age groups doing? Different ethnic groups? It's grim reading.