I attended a meeting of a community of practice in the Netherlands, for teachers. I was again struck by the fact that a community of practice is a place where you can share with peers what you are passionate about in your work; peers who will listen (because they recognise it from a deep understanding) and appreciate it.
One of the teacher had worked for two weeks on a database system to keep track of competence development of pupils. When asked if he had so much time at hand to work on it, he answered that he did it partly in his own time, as a hobby. This community meeting was a place where he could share that- partly voluntary- work.