A little article summarizing a paper by economists, who claim that preschool is the best investment. The writer cites the Perry Preschool project, but unfortunately makes the statement, "there appears to be nothing special or unique about the Michigan preschool". I would have to say that the Perry Preschool was quite a bit different than the other preschools of the day, pioneering teaching young children in a hands-on, child-centered context. But hey, that's just my opinion.
You can read the article here, and if you are eligible for a free download, you can read the paper here.
More information about the Perry Preschool Project is here.