A CoP cannot be mandated, but can be formed, encouraged, and nutured.
This researcher has been encouraging the formation of communities of practice with a set of practitioner faculty, working on a part-time basis and under normal circumstances, would have little interaction with each other, let along meet with anyone.
Formal meetings are held periodically, but with new faculty coming and going, social relationships are temporary.
The challenge has been to find ways to encourage something more ongoing than periodic meetings and and whatever networking opportunities these meetings bring.
Many of the same technologies that support virtual teams have been found effective in supporting CoPs, such as the Internet and Websites for hosting project information, best practices, and so on.