For the technical professionals that come to experiences like MSDN and TechNet the four types of communities seem to be most pertinent:
support based communities
communities of practice
Support based communities are probably best characterized by the need for an answer now. This is manifested on our forums today. Most technical forums seem to fall into this category.
Communities of practice tend to be those types of communities that draw people in around a shared goal -- learning more about a particular topic for example. In many ways, groups such as Ineta and Culminis appear to fall into this category. Another example,
Feedback/development based communities are those where people interact for the sake of bettering a product or technology while getting early previews as to what's next. Connect seems to be a prime example of this. Dell's IdeaStorm is
Enthusiast communities are those where people tend to interact with others to not only connect with those that share their enthusiasm, but also to share their passion around a particular product or technology. Channel 9 (in addition to Channel 8 and On10) do a nice job of this. I'm not an expert on enthusiast or fan-based communities, but Nancy Baym and Henry Jenkins have both written a lot about this.
Of course, there are many more types of communities. I only listed four different ones as they seem to be most pertinent to the work I do. To clarify, in working on a communities team, I am not responsible for all the sites/experiences listed above. Rather, those are just examples to better illustrate what I mean by community types. My role now focuses more narrowly on planning for community from a platform and processes perspective. I am of the notion that the platform and processes needed will vary based on the types of community being discussed.
So that's where my head is at right now. What do you think? Are there other types of communities pertinent to technical professionals in your opinion?