don't think of an elephant: Know Your Values and Frame the Debate-- The Essential Guide for Progressives by George Lakoff

Lakoff has emerged as a leading language guru for the liberals and progressives. He explains how "framing" affects everything, how the "conservatives" (that's a frame) have defined liberals and beat the pants off progressives at the polls.

More that that, Lakoff shows how to reframe the positions more to our liking and to begin to win the debate again.

Like it or not, George Bush won the last election; reading this book will help you understand how that happened. Very short and readable, most readers can blow through it in a weekend.