The Movable Type Open Source Project was announced in conjunction with the launch of the Movable Type 4 Beta on June 5th, 2007. The MTOS Project is a community and Six Apart driven project that will produce an open souce version of the Movable Type Publishing Platform that will form the core of all other Movable Type products.
Movable Type Open Source, or MTOS, is the open source project that will consist of a GPL-licensed version of Movable Type 4.0, to be released in Q3 2007, and resources for the already large community of Movable Type developers, hosted at www.movabletype.org/opensource.