Guy Kawasaki has some straight forward advice for creating community that would serve use well to revisit. And, he does refer to the Photoshop community as an example of how to do it right.
In his posting, The Art of Creating a Community, he explains his eight steps in detail.
1. Create something worth building a community around.
2. Identify and recruit your thunderlizards—immediately!
3. Assign one person the task of building a community.
4. Give people something concrete to chew on.
5. Create an open system.
6. Welcome criticism.
7. Foster discourse.
8. Publicize the existence of the community.