How does customer development differ with regards to products which require a network effect to be useful?
Short answer: No one knows.
Companies offering services such as Skype, eBay, Facebook, and others have cannot really test their value proposition without having a critical mass of users. A telephone with only one person on it is pretty useless. Yet these are some of the most lucrative inventions ever. So how do you apply the principles of customer development to these situations?