Plan 9 Is Now Available Under The GNU GPLv2
Plan 9, the Unix replacement at Bell Labs since the 1980's for operating system research that ultimely disbanded in the early 2000's, was under the Lucent Public License. The Lucent Public License is considered to be open-source by the OSI and FSF, but now Alcatel-Lucent (the corporate inheritor of Bell Labs) has authorized UC Berkeley to make all of the Plan 9 software available under the GPLv2.
Plan 9 is under the GNU GPLv2 so parts of it code can be incorporated into Berkeley's Akaros project. Alcatel-Lucent apparently intends to continue to distribute its LPL-licensed Plan 9, thus basically making it dual-licensed, but the GPL version can be obtained from Berkeley.edu.
Those wanting to investigate Berkeley's Akaros can find the project site while the official Plan 9 continues to be available from Bell-Labs.com.