Anyone else catch Seth Godin's latest move?

Seth Godin tries a clever variation on Groupon to gather signups for his newsletter. The more people that sign up, the lower his product's price. He'll lower the ebook price by $1 for every 5,000 people who sign up for his free online newsletter. So far it's down from $9.99 to $7.99. Are you signing up? Details here.