Adhocracy is, as it sounds, ad hoc governance, where individuals act as they see fit in order to achieve a collective goal. See the Wikipedia article on Adhocracy. This form of governance is fairly typical of open source software projects, especially in their early stages.
The Startup group of the Metagovernment project mostly is run as an adhocracy. However it intends to be run as an collaborative governance structure as soon a pre-release version of Metascore is available. This is called "eating one's own dogfood."
At some point, there may also be a need for a formal organization to perform some administrative and interface tasks.