I am still not sure about Communities of Practice and I am not sure Affinity Spaces are the answer. The thing is that many of us have used the Communities of Practice model to understand online communities but there is a real probem with notions of membership and boundaries etc which are really not an accurate descriptin of the dynamics which seem at once intensive and dynamic. Temporary coherences. Affinity spaces, first talked about by Gee I think, (and building on his idea of the semiotic domain) evolved as a term around online gaming, but again I m am not sure it is properly transferrable as a model for non gaming online groups, although I, like Michelle Knobel, have also used this term.
In this book, Massey talks about ‘constellatons of temporary coherences’ in regard to groups of youth meeting - but is not talking about cyberspace, but I think it could be applied to online groups and want to think more on this.

In Flickr people belong to lots of different groups; the whole site does not really constitute a coherent community it is a series of groups.
Individuals in the groups interact with each other and some belong to numbers of groups where they meet again.
They have in jokes, interests and conversations which are thematically dropped and picked up again.
Individuals carry across specific identities and social histories. These are shown multimodally in words and images and in the associations they trace across the groups.
Individuals seem to develop online identities and coherences.
they teach each other.

Some groups are VERY popular and there are some definite stars on the board;movers and shakers who influence.

There are some individuals who start groups which no one joins.
I have seen one big argument and this I think is an unusual occurence although I have spotted this too.

Finally there is this fab new thing I have been invited to join. The Flat Stanley Project is a very exciting idea in my opinion and there is also a blog to go with it.
So it is an example of online learning collaboration across generations. I think itis antastic the way adults are invited to help in the education of children in this way..