Here's an interesting site, which I found found from a intelligent comment on an earlier post. It explores the problems faced by young adults in their late twenties, applying some of the recent findings of positive psychology to issues like career choice and values. It looks like a serious attempt to grapple with an extremely important issue - beset by student debt, rapid economic change and changing social structures, young adults have a hard time.
One interesting thing I'd like to read as well is international comparisons. Are choices simply harder in recessionary times, or is there a broader international issue of "failure to launch" with deeper underlying problems? Japan has its herbivores, for example. Italy has its adults living at home well into their thirties.