I know of a few nonprofits that like to think of themselves as "movements" -- but very few of them actually are. The Brains on Fire Blog takes a nice look at the difference in Campaigns vs. Movements:
Campaigns have a beginning and an end. Movements go on as long as kindred spirits are involved. Campaigns are part of the war vocabulary. Movements are part of the evangelist vocabulary. Campaigns are dry and emotionally detached. Movements are organic and rooted in passion. . . . Campaigns are you talking about yourself. Movements are others talking about you. Campaigns add to awareness. Movements add to credibility. Campaigns are "you vs. us." Movements are "let's do this together."
Movements are a little bit "out of control." But they're a lot more exciting than campaigns, and they can accomplish a lot more.
Never mind the difficult fact that getting a real movement started is something you can't just pull out of your hat like a piece of direct mail. First, ask yourself: Would I be willing to give enough power to my donors to become a movement? Because I can almost guarantee that where fully empowered movement-driven donors will take you isn't exactly where you think you're going now. It's someplace better, but that's beside the point.
Until you're ready to give up control, you'll never be a movement.