Being open is core to the goals and objectives of Peerlibrary. The landing page was changed recently too to reflect the same - Open Knowledge. Open Access. Open Source. I feel that the project is open mostly because of ideological reasons. It is because the group truly believes in openness. It would be a complete paradox if the group that believes so strongly in open access to science and research would itself be closed and locked in. Furthermore, I reason that there are some practical reasons behind making it open source. The vision of Peerlibrary is to become the hub of all science done in the future. If Peerlibrary needs to be sustained well into the future it makes practical sense to keep it open, so that others can contribute and take it forward in the future and keep evolving continuously.
The community is very small with 5 people who meet regularly at the Berkeley Institute of Design ( BID Lab ). All the members are from Berkeley so meeting up is easy. Once Peerlibrary goes live there will be more contributors. I feel that most ideology discussions happen face to face, but most coding decisions and issues are all tracked online. There is a mailing list and an IRC channel on freenode. Personally, I have used the mailing list, but haven't used the IRC chat enough.
Peerlibrary is licensed under the AGPLv3 copyleft license.
I think I joined this community because I felt really strongly about the cause that it supports. I don't really know what I would have done differently if I knew the things that I know now. My experience has been very pleasant and I'm learning something new everyday. The biggest hindrance for me has been learning something completely new like Meteor and even learning the intricacies of the collaborative development process at Peerlibrary (e.g: the use of branching, pull requests, issue tracker etc.).
added Comments Thomas 11/6/2013 (see commit description)