Scotch (and its parallel offspring PT-Scotch) is a scientific toolbox for graph partitioning, static mapping, clustering and sparse matrix ordering : http://www.labri.fr/perso/pelegrin/scotch/

Scotch is widely used by many academic and industrial entities, either by itself or through other well-known software packages such as MUMPS, OpenFOAM, etc. It is distributed under the CeCILL-C libre software license. This year 2012 was the 20th anniversary of Scotch. For this occasion, version 6.0 was released, which introduced many new features. It is the occasion to present how the project was started, how it evolved, how it could gain momentum, and discuss licensing and organisational matters.