http://www.nytimes.com/2009/07/06/us/06retrain.html?ref=us From the self serving NY Times.
Nonetheless, a little-noticed study the Labor Department released several months ago found that the benefits of the biggest federal job training program were “small or nonexistent” for laid-off workers. It showed little difference in earnings and the chances of being rehired between laid-off people who had been retrained and those who had not. In interviews, the authors of the study and other economists cited several reasons that retraining might not be effective. Many workers who have lost their jobs are older and had spent their lives working in one industry. In need of a job right away, many pick relatively short training programs, which often have marginal benefits. Job retraining is also ineffective without job creation, a point made by several economists who have long cautioned against placing too much stock in it. Finally, workers trying to pick a new field cannot predict the future of the labor market, especially in a time of economic upheaval.