History of OpenSolaris

OpenSolaris was based on Solaris, which was originally released by Sun in 1991. Solaris is a version of UNIX System V Release 4 (SVR4), jointly developed by Sun and AT&T to merge features from several existing Unix systems. It was licensed by Sun from Novell to replace SunOS.
Planning for OpenSolaris started in early 2004. A pilot program was formed in September 2004 with 18 non-Sun community members and ran for 9 months growing to 145 external participants.

Sun submitted the CDDL (Common Development and Distribution License) to the OSI, which approved it on January 14, 2005.
The first part of the Solaris code base to be open sourced was the Solaris Dynamic Tracing facility (commonly known as DTrace), a tool that aids in the analysis, debugging, and tuning of applications and systems. DTrace was released under the CDDL on January 25, 2005 on the newly launched opensolaris.org website. The bulk of the Solaris system code was released on June 14, 2005. There remains some system code that is not open sourced, and is available only as pre-compiled binary files.
To direct the newly-fledged project, a Community Advisory Board was announced on April 4, 2005: two were elected by the pilot community, two were employees appointed by Sun, and one was appointed from the broader free software community by Sun. The members were Roy Fielding, Al Hopper, Rich Teer, Casper Dik, and Simon Phipps. On February 10, 2006 Sun approved The OpenSolaris Charter, which reestablished this body as the independent OpenSolaris Governing Board. The task of creating a governance document or "constitution" for this organization was given to the OGB and three invited members: Stephen Hahn and Keith Wesolowski (developers in Sun's Solaris organization) and Ben Rockwood (a prominent OpenSolaris community member).
Initially, Sun's Solaris Express program provided a distribution based on the OpenSolaris code in combination with software found only in Solaris releases. The first independent distribution was released on June 17, 2005, and many others have emerged since.
On March 19, 2007, Sun announced that it had hired Ian Murdock, founder of Debian, to head Project Indiana, an effort to produce a complete OpenSolaris distribution, with GNOME and userland tools from GNU, plus a network-based package management system. The new distribution was planned to refresh the user experience, and would become the successor to Solaris Express as the basis for future releases of Solaris.
On May 5, 2008, OpenSolaris 2008.05 was released, in a format that could be booted as a Live CD or installed directly. It uses the GNOME desktop environment as the primary user interface. The later OpenSolaris 2008.11 release included a GUI for ZFS' snapshotting capabilities, known as Time Slider, that provides functionality similar to Mac OS X's Time Machine.
In December 2008 Sun Microsystems and Toshiba America Information Systems announced plans to distribute Toshiba laptops pre-installed with OpenSolaris. On April 1, 2009, the Tecra M10 and Portégé R600 came preinstalled with OpenSolaris 2008.11 release and several supplemental software packages.
On June 1, 2009, OpenSolaris 2009.06 was released, with support for the SPARC platform. On January 6, 2010, it was announced that Solaris Express program would be closed while an OpenSolaris binary release was scheduled to be released March 26 of 2010. The OpenSolaris 2010.03 release never appeared.
On August 13, 2010, Oracle was rumored to have discontinued the OpenSolaris binary distribution to focus on the Solaris Express binary distribution program. Source code would continue to be accepted from the community and Oracle source code would continue to be released into Open Source, but Oracle code releases would occur only after binary releases. Internal email was released by an OpenSolaris kernel developer but was unconfirmed by Oracle.

There was a post confirming the leak posted to the OpenSolaris Forums on August 13, 2010. Upstream contributions will continue through a new Oracle web site, downstream source code publishing will continue, binary distribution will continue under the old Solaris Express model, but release of source code will occur after binary cuts, and binary cuts will become less frequent. On September 14, 2010, OpenIndiana was formally launched at the JISC Centre in London. While OpenIndiana is a fork in the technical sense, it is a continuation of OpenSolaris in spirit: the project intends to deliver a System V family operating system which is binary-compatible with the Oracle products Solaris 11 and Solaris 11 Express. However, rather than being based around the OS/Net consolidation like OpenSolaris was, OpenIndiana will become a distribution built up around Illumos kernel (the first release is still based around OS/Net). The project does use the same IPS package management system as OpenSolaris.