According to wikitionary, it means "An amateur, someone who dabbles in a field out of casual interest rather than as a profession or serious interest."
)Mostly, it refers to the arts) I dabble in a lot of fields superficially - especially the arts. I've been successful in generating a more-than-amateurish interest in photography and the written word. Hence most of my bios online have "A very successful dilettante" written up!