movabletype.org: Welcome to MTOS: the Movable Type Open Source Project

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.

This looks like something worth looking into.