Work is progressing on Mukurtu as we develop the system around hosting content with multiple and overlapping permissions categories. The underlying architecture is based on the open source Drupal content management system combined with Organic Groups and the Views and Panels modules.
There have been major changes in the way that Drupal (and these other modules) approach content in the latest release (v7) because content is now managed in terms of entities and fields rather than as nodes. In other words, rather than managing information in terms of entire webpages each field of data on that page (title, description, images, text fields1-2-3, tags), these are managed separately. This provides finer grained control over what portions of content are shared, and with whom.
This should allow administrators of Mukurtu-based sites to be able to host content items surrounded by panels showing associated information about the group(s) to which the content belongs, associated tags, and other relevant information -- all customized to the viewer and their permissions.