I heard their founder/current CEO Yancey speak at a startup accelerator and speak extensively about the business. According to him they told their investors they have no intention to have a liquidity event. He suggested the investors were in interested in Kickstarter as marketing for their firm. It seems like they didn't take very much money. Seemingly a large enough sum to help grow the business but not large enough to shy investors away from a business that doesn't aspire to provide meaningful returns.
Have you listened to the Startup podcast's coverage of Gimlet media? Seems like a similar situation, some unique businesses can secure prestige rounds providing they are not seeking huge amounts of capital.