The partners released the first snapshot of the OS on September 15, 2009 with a second being released in March, 2011. Excluding some third-party libraries, which are covered by various BSD-like open source licenses, Barrelfish is released under the MIT license. Snapshots are regularly released, the last one dating to January 29, 2015.
Andrew Baumann, Paul Barham, Pierre-Evariste Dagand, Tim Harris, Rebecca Isaacs, Simon Peter, Timothy Roscoe, Adrian Schüpbach, and Akhilesh Singhania. The Multikernel: A new OS architecture for scalable multicore systems. In Proceedings of the 22nd ACM Symposium on OS Principles, Big Sky, MT, USA, October 2009.
Pierre-Evariste Dagand, Andrew Baumann, and Timothy Roscoe. Filet-o-Fish: practical and dependable domain-specific languages for OS development. In 5th Workshop on Programming Languages and Operating Systems (PLOS), Big Sky, MT, USA, October 2009.
Andrew Baumann, Simon Peter, Adrian Schüpbach, Akhilesh Singhania, Timothy Roscoe, Paul Barham, and Rebecca Isaacs. Your computer is already a distributed system. Why isn't your OS? In Proceedings of the 12th Workshop on Hot Topics in Operating Systems, Monte Verità, Switzerland, May 2009.
Adrian Schüpbach, Simon Peter, Andrew Baumann, Timothy Roscoe, Paul Barham, Tim Harris, and Rebecca Isaacs. Embracing diversity in the Barrelfish manycore operating system. In Proceedings of the Workshop on Managed Many-Core Systems, Boston, MA, USA, June 2008.