The current version of The New Yorker has a wonderful article by Jonah Lehrer called “Groupthink” (you can see the abstract here). It does a great job of showing how creativity is a social process, cites wonderful research by Brian Uzzi showing that when people have experience working together in the past they produce more successful Broadway musicals (up to a point, too many old friends is as bad as too few), and offers research showing that groups where members engage in constructive conflict are more creative — all themes I have talked about at various times on this blog.
I do however have a major quibble. At one point, Lehrer states flatly that brainstorming doesn’t work. He later quotes creativity researcher Keith Sawyer as saying that people are more efficient at generating ideas when they work alone than in groups, something that is well-established. But that is not the same as saying there is conclusive evidence they don’t work.