The goal here is to pair up Nader supporters in swing states with Kerry supporters in deep red or deep blue states. Nader gets his vote in the national popular total and Kerry gets strategic electoral help. Have your Nader and your anti-Bush too. Everybody wins! Well, except for GWB, we hope.
Electoral-vote.com calls this The Law of Conservation of Naderism.
I won't vote for Nader in Illinois for the sole reason of spite. I resent that he decided to run despite the stakes; I would've voted for him in 2000. Also, he's not on the ballot. And he's not running under the greens anyway, so it wouldn't secure anything in the future.
I have no plans of voting for Nader either. But if this gets Kerry a few more votes in Ohio or Wisconsin from some people who do it, great.