The latter requirements (interesting project, high amount of autonomy, non-capricious requirement) does, however, exclude the typical "I'm an alpha-male with an MBA who can't code, I need a beta-male coder to implement my vision"
situations. I have a very strict requirement when joining other companies: I can't absolutely be the smartest or most technical person in the company.
Several times I've worked on side-projects/ideas that could bloom into something and I am not opposed to starting a company to pursue that, along with another technical founder. Being a founder also means the ability to completely set the technical direction, something you can't quite get when joining as an employee (corollary: if you can't set the technical direction of a company, you're not a founder).
Success in a start-up requires drive, solving fascinating technical problems drives me. I've absolute zero interest in being involved in media or enterprise-y start-ups (either as a founder or an employee), no matter how much money is dangled in front of me.