It’s important to contrast an MVP with a smoke-test approach where you build a teaser site — for example, a simple page generated in LaunchRock with links to social networks. With a smoke-test page, you’re testing the risk that the message isn’t compelling enough to get signups. With the MVP, you’re testing the risk that the product won’t solve a need that people want solved in a way that will make them permanently change their behavior. The former tests the problem messaging; the latter, the solution effectiveness.