Chris Brogan nails it in today's post, Stop Adding Me to Your Email Newsletter.
He posits, "Unsubscribing is the easy next step, but then what? I sure don’t feel vindicated just by unsubscribing and saying, “I never signed up to begin with” as my reason for leaving."
He then continues with a frank e-mail response that he encourages everyone to copy/paste whenever they find themselves in similar circumstances.