The Chicago Boyz, a blog on economics, has an interesting assessment of the value of labor. I have always been of the opinion that labor had its own value, but that it was enhanced by the addition of management and capital. That is, if you are a worker, even if you have the tools of your trade, by yourself you will not be able to achieve as much as if you have other people who are working to secure future work and clients, or coordinate improvements to make the worker even more productive.
The ideas of many (like Mark T.) seems to be that management is but a parasite, sucking the productivity from the worker. The article above certainly puts another, more plausible explanation.
UPDATE: Link broken before, hopefully it's fixed now. Thanks Andy.