Paul Graham has something to say about professionalism vs. amateurism, which goes nicely with my comments in May.

I suspect professionalism was always overrated— not just in the literal sense of working for money, but also connotations like formality and detachment. Inconceivable as it would have seemed in, say, 1970, I think professionalism was largely a fashion, driven by conditions that happened to exist in the twentieth century.