The rigorous evidence on vocational training programs is, at best, mixed. For example, Markus recently blogged about some work looking at long term impacts of job training in the Dominican Republic. In that paper, the authors find no impact on overall employment, but they do find a change in the quality of employment, with more folks having jobs with health insurance (for example).
One popular solution to unemployment is to provide the unemployed with more skills through training. However, the impacts of vocational training in developed countries have been at most modest.