I think that the SWJ site (the collective whole of the Journal, Blog, Discussion Forum and reference areas) is a good way to actually structure a matrixed and dispersed (maybe virtual) organization.
In the military, there is a plethora of "Centers of Excellence" being created. Beyond the usual jokes about the name, the attempt is being made to gather the threads of some critical warfighting mission, capability, aspect, etc. and create a focal point to facilitate organizing the knowledge in hopes of better dissemination (education and training) and being the advocate for new/better ideas and systems.
I've heard a couple of business presentations and one thing that sticks out is the contention that it is easier to organize around the software than to make the software adapt to a pre-determined organization. I think that the SWJ site could be a model for similar official sites to provide a focal point to discuss and assist in knowledge dissemination, etc. Sort of like what COEs are attempting to do.
As to blogging specifically, as a planner (experience at MEF, JTF, MNF-I and Fleet levels), I think that the discussion board and blog are a great model for managing deliberate planning efforts. Current Ops folks use chat rooms to coordinate in real time. Planners, especially at the higher echelons, don't need that immediate real time response, but need to handle and track multiple issues over the course of time. I could easily see an effort involving multiple HQs organzing the planning around a discussion board type organization.
The problem I have had in trying to implement this is that the military is more comfortable in trying to use email for this purpose, or to just post things in folders on websites. I think this idea will take off more as the younger generation who are growing up with it "come of age" into the field grade ranks (if they choose to stay past Captain).