I want to add another point to this discussion. So far we could always say that for lilypond sources, there is mutopiaproject. Unfortunately, it seems that this project is currently out of people who have enough time to do the administrational stuff. So it seems as if sooner or later, mutopiaproject is going to die or at least not to grow any further. Hence, it would be desirable to have an additional port for these scores (CPDL is possible in principle, but only for vocal works).