John Seely Brown, chief scientist at Xerox, wrote a classic article "Growing Up Digital" with some great examples of, for example communities of learning and practice among (of all things) photocopier technicians at Xerox.
Clay Shirky's (2003) paper "A group is its own worst enemy", is a fascinating exposition of the challenges involved when a group tries to work collaboratively.
The Lattecentric Ecosystem is an interesting article by Stephen Downes in which he responds to the criticism of learning objects that they result in bland courses with no sense of flow. He first (rather effectively) draws analogies to many other larger systems (such as a Shakespearean sonnet) constructed from discrete objects. Second, he endorses the idea of course material being somewhat 'disassembled' and assembled into coherence in the course of instruction - mostly by students. "I have long felt that the attempt to organize bits of instruction into neatly packaged courses is a mistake. That does not mean that the presentation of materials to students is completely without order: rather, it is to argue that the grammar of such presentation is not, should not be, a linear sequencing of prepackaged learning events, a presentation in which the student is nothing more than a mere spectator." The kind of coherence instructors and students should impose on learning materials is of the form of a network and the complexity level of the network should be somewhere between having each node connected to each other node and being a simple linear sequence.
"The art of instructional design, therefore, comes in the placement of a student somewhere within that ecosystem and the identification of relevant connections. The student, by navigating (perhaps in some goal-directed way, perhaps out of curiosity and interest - this is part of the design) therefore creates a new entity, perhaps by identifying new connections, perhaps by deducing abstractions already present (but not revealed) in the network, perhaps by an analysis of the nature and role of component parts." The lattecentric part of the title comes from the fourth of Gilly Salmon's four educational 'worlds' - Cafélattia, which features learning communities, communities of practice, professional development and instructors as moderators. "Educational design, in the first instance, therefore consists in the creation of these environments, of the writing of a (modified and perhaps restructed) version of the thesarus, making a certain relevant set of objects available for discourse, or providing the tools for and motivation for interaction and the construction, either individually or in groups, of new entities"
Also (again) argues for 'multiple semantics' - "we need to be able to use various flavours of learning object metadata to describe learning objects". Also: "the structure of a learning object network should resemble that of an RSS network". RSS is Rich Site Summary - a metadata markup system for web content used by thousands of news-oriented sites to harvest fresh information from sites (such as Stephen's) that make their content available as RSS files. What Stephen argues for here is a 'distributed learning object repository network' (DLORN) which can be accessed via something like a 'learning object browser'.
Books
Also see the collaborative learning biography drawn up by Kathryn Plank, Diane Enerson, and Neill Johnson and the section on communities of practice in this book.