I'm finally coming back online.. I had to deal with a nasty cold (bad enough as to raise some N1H1 paranoia :D) and a broken laptop... But anyway...
I have the feeling that it depends on the purpose behind the idea of network of communities... From what I've seen, in your case (Paul) it has to do with sharing community practices (and maybe getting some kind of 'scale economy'?) and getting people from different communities in touch with each other.
Now, to my particular context, it has to do with information serendipity. I'll try to explain my point. Let's say that people in this seminar are very good managing information overload, and they do know how to get access to new, unexpected, interesting and relevant information.
Now it's clear that (at least in the Colombian scenario) most of our teachers don't have this ability. Maybe some of them are e-mail power users, and maybe others use the educational portal we have, or some existing community platform. Add to this the different online communities and services many of them use, and it becomes apparent there are a lot of useful information that is not visible, just because people are part of networks that don't necessarily overlap.
That was a huge issue with Ning until a couple of months ago. Many of us were part of way too many communities, and the info was too dispersed to be useful. In April they made possible to follow network activity from a single entry point (sort of a personal page), which makes things way easier...
in my view (and for our particular problem), if we could get the info many of our communities are generating in some system, and get some single sign-on solution for all of them, maybe there could be a chance to add value to current users, suggesting relevant information placed in networks/communities the user is not part of.
I'm still having a hard time trying to make sense of all this (so it could make no sense at all :D), but such a system should be 'transparent' enough as to suggest the info and then lead people to the places where interactions are taking place. This means that, in my view, such a system is not really 'another network/community', but a personal hub where I get new pointers to relevant information, generated elsewhere.
This means that maybe such a system would not really require a facilitator, because the community interaction goes unaffected. Think of it as you would think of Facebook, for example. In FB, people create groups and communities, but there's no one from FB in charge of helping people to 'enhance' their community experience (which, by contrast, happens in some way in Ning).
What I'm seeing is that the things I'm talking about could be tied (or not) to an initiative like LTC. If a 'network of communities' means a new space for interaction, there are some things worth exploring ,like John suggests. If interactions happen elsewhere, there are a different set of issues to discuss.
There's something else I'd like to point out. Even in our case (Colombia) there are different approaches for the same thing. As we'll see later in the seminar, there are another approach (related to higher education online communities) closer to the LTC experience than the one I'm talking about. I'd say I'm more concerned with personal access to information, in addition to the community issues.
Happily, this is intended to be an exploratory seminar :D, so it makes sense to realize that there are a lot of subtle differences in our approaches, which is normal because we're coming from different needs.
I'm sorry about this long post... I guess I took advantage of you all to clarify my ideas a little bit! :D