Transterrestrial Musings linked to this MSNBC article, which talks a bit about the regulatory hurdles to space flight. Here is an interesting paragraph, bearing on the costs of certification I discussed below (in the comments).
Another savvy decision by Rutan: He won’t put SpaceShipOne through the FAA certification necessary for commercial aircraft to carry passengers. That process, which can take years, has cost firms like Boeing and Airbus up to 10 times the price of development.