Henry Blodget has a quick primer on this topic, with some graphs and charts of interest. My view is simple. I see two major risks:
1. The currency-area-formerly-known-as-the-eurozone unwinds and Europe spirals into a major recession, taking down much of the world with it.
2. China implodes economically, taking down much of the world with it.
If neither of those two events happens, we should continue to see a recovery, with fits and starts, but a slow one in the labor market.
In other words, I'm still not an economic optimist, but I do have a rosier view of the default course than do many other commentators. I just don't think the shocks have finished arriving.