APIs and Copyright - Monopolizing Ideas or Affording Protection?

Should APIs be covered by copyright law? Would developers and innovation be stifled by copyrightable APIs? Or would it afford protection over IP (Intellectual Property)?

The EU has ruled that APIs are not copyrightable and the jury was literally still out in the USA when the Apigee team got together for a discussion of the pros and cons, and the potential consequences if APIs are held to be copyrightable.