I'm excited about the latest installation of the open-source ELGG platform, called TeacherEd, not because it's anything earth-shaking (although it appears to be an excellent start), but because it shows how easily the application can be adapted to different purposes. At its core, it's basically a blogging application with the ability to host and share files, but it also has functions for forming communities with user-defined permissions on everything. It was originally billed as a type of e-portfolio application, which it certainly could be, but I'm thinking that other possibilities may be more fruitful.
I'm thinking that ELGG could be used as the platform for association and club web sites -- basically any group of people who want control over who sees their content and interactions. For example, our local citizens' association could have sections that were open to the public (news, membership info, links and documents) as well as private discussions or strategic documents that were only for members. Members could form project teams with their own posts and files, and individuals could post their individual feedback and research. It would be more personal and accessible than a discussion board, less annoying than a listserv and more flexible than the group blog we've got now.
Perhaps this is an example of how the web is changing and a possible display of how powerful it could be for groups. The tools themselves have been around for a few years, but the application of free, open networking software to very specific niches is where things could really take off. What about study groups and homeschooler networks, sports clubs and project teams? Dave and Ben have done great work here, and I think it's only a matter of time before customized versions of their alpha applications (and the related work of others) are changing the way groups interact online.