I read this article today: http://www.ere.net/2012/04/18/are-you-hiring-deciders-or-drifters/
I agree. Most of my clients are looking for people who feel confident that they can figure out the problems that are weighing on their organization and fix them. They want people that can make decisions.
The best way to prove that you are this type of person is to first, ask questions about their pressing problems or the problems specific to the position you're interviewing for. Second, give them a map of how you would go about solving the problem and/or how you've solved similar problems in the past.