After a lot of hard work, Jamoma 0.4 has been released. This is a major upgrade from 0.3, the most important being that now all the core objects have been ported to C which makes everything run much faster. Lots of other things have improved as well, the only drawback being that 0.4 breaks compatibility with 0.3.
Installers for Mac and Windows are available from the Jamoma page.