"First, what do we mean by “open?” Open refers to a common space that cannot be enclosed by any individual, organization, or government. A common space is owned by all, regardless of nationality, affiliation, employment, or ideology. A common space may refer to something tangible, such as air, or something intangible, such as knowledge. Free speech could be thought of as an "idea commons." In other words, a commons is a space which, by definition, is not enclosed or controlled.
We assert that the “currency commons” refers to the capacity that communities have to agree on how to measure and interact with flows of resources that matter to them. We also assert that the right of groups of people to agree on how to measure what they care about is as inalienable as the right to free speech. However, without intending to, most currency projects end up enclosing this space in some way." (http://blog.newcurrencyfrontiers.com/2009/07/open-currency-now.html)