Ok, this just isn't news enough yet to post it on the frontpage, but I just got off the phone. Michiel de Vries had been working on Meridian a lot. An instrument editor for 2-operator FM, 4-operator FM and WAVE is already impelemented. It will be possible to use custom samples! Also, Michiel thinks it will not take extreme adjustments to allow MOD and S3M support.
The downside is that you'll need a 1024KB mapper in order to be able to work with Meridian. But who cares, THIS ROCKS!