NOTE: The TSK Framework has not been included in an official release yet.
The original goal of TSK was to provide platform independent access to all types of volume and file systems. The framework expanded that goal to include application-level analysis so that there would be an open source end-to-end solution for digital investigations.
Much of the documentation for using the framework is included in the source code documentation . This wiki page contains links to pages that can be updated and edited by framework users.
This will move with a content reorganization, but here is a related link to getting the source with git.