I've got a working core - all the functionality to connect plugins and produce sound are there (that's Audio::LADSPA::Network plus a few additional plugins), and there's a functional GUI for it, including loading & saving networks.

Currently I'm working on the sequencing part, which still needs a lot of GUI work. I don't know when that'll be done, since I'm also pretty busy doing paid work.

By the way, I've just uploaded the latest version (0.018) of Audio::LADSPA to CPAN. This doesn't include the GUI but at least it allows you to play around with any ladspa plugins you might have installed.