Michael Shermer says 'No':
"Of course, no one is agnostic behaviorally. When we act in the world, we act as if there is a God or as if there is no God, so by default we must make a choice, if not intellectually then at least behaviorally. To this extent, I assume that there is no God and I live my life accordingly, which makes me an atheist. In other words, agnosticism is an intellectual position, a statement about the existence or nonexistence of the deity and our ability to know it with certainty, whereas atheism is a behavioral position, a statement about what assumptions we make about the world in which we behave."
http://www.skepticblog.org/2012/04/10/are-you-an-atheist-or-agnostic/