Mine is http://mobeeknowledge.ning.com (MOBEE KNOWLEDGE CoP) The theme : “Toward next generation KNOWLEDGE MANAGEMENT 2.0 through contextual learning on the issues of TECHNOLOGIES, MARKET, PEOPLE and INNOVATION”
I am new to Ning and have the one site (3 or 4 months old) which is aimed at SME's within Cork (Ireland). One of my biggest sources of traffic, according to Google Analytics, is Twitter and LinkedIn. Most of my networks on these sites are local to me so I find them a good source.
Another useful one (which surprised me to be honest) is the invite option. I can see from my Admin area that 300+ invites have gone out.
I'm not aware of any Ning rule changes (may be this was before I joined?).
Oh, ok, I haven't done this so guess that was before my time.
You must be a member of those other networks then Mark, so presumably you could log-in to each separately an send a message to your friends on that network. Obviously a longer process but the outcome/uptake should be the same, I would have thought.