The value of the tool is only as good as the participants make it. Members will be compelled to participate when there is good information available that will help them do their job better or consistent interaction such as comments to a blog post or responses to a forum post. In order to really understand it's value, members shouldn't view it as "just another thing to do", but as an extension of what's already being done. When groups are already meeting face to face on a regular basis, specific goals emerge and follow up becomes important. That's when the asynchronous nature of communication can really enhance the development of ideas and making plans for follow up.
This tool is not without it's issues, although the issues are not so disruptive as to discourage the users from participating. First of all, it's important to note that Ning is not Facebook, but it's open to any group of people, not just educators. Some content or subject matter may be offensive to some. In addition, Ning is open to spam in the form of unwelcome requests for membership from people who are trying to gain exposure for commercial purposes. Access to the content and membership can be carefully controlled by the privacy settings, invitation only, and the ability to moderate by the Ning organizer. Finally, unless the organizer pays for premium service, Ning includes Google ads on the right column of the page. Some find the ads distracting.
Check out these rich communities that utilize Ning to collaborate with educators all over the world that have been set up by an organizer to share resources or help facilitate support for it's members to enhance their teaching practices:
Smartboard Revolution - share tips and resources on using interactive whiteboards in the classroom
ISTE Commnity - The International Society for Technology in Education organizes this site for it's members to collaborate
Teacher Librarian Network - developed for teachers and school library staff
The English Companion - very active community of English teachers who are there to help others
Classroom 2.0 - extremely large group of teachers who interested in using technology in the classroom, a great place for beginners
Fireside Learning - an opportunity for anyone to reflect on teaching practices and anything about education
Gifted Education - a community of teachers who are intereted in helping each other when working with gifted students
Art Education 2.0 - a global community of teachers who use Ning to facilitate the use of new technologies in Art class