Good thing the Sun Blackbox is just a concept for the future and not selling yet. On the serious side, a portable and self contained data center sure has some merits, besides getting Sun in the news.
Some of the scenarios for the Sun Blackbox make actually sense if the servers inside the containers actually do not need requirements from the location where they are located (e.g.: air conditioning).
Tons of project Blackbox material on the SUn site.