There is a VST plugin that runs Pure Data patches
http://pd-pulp.net/
The Oxe FM synth is now available as a native Linux VST
https://github.com/oxesoft/oxefmsynth
There is a Renoise tool that provides an interface for the processors
from the Composers Desktop Project.
http://forum.renoise.com/index.php/topic/41882-new-tool-30-cdp-lua-tool/
Nick Dowell's amSynth now works as a native Linux VST
http://amsynth.github.io/
RtCmix has the beginnings of an IDE useful for Linux users
https://github.com/jwmatthys/cmixide
Commercial interest is higher than ever, with samplers from Renoise
(Redux) and discoDSP (Bliss), synths from u-he, discoDSP (Vertigo), and
Tracktion (MicroSynths). Bitwig continues its climb towards a 1.2
release, the betas finally have JACK transport control and support for
loading FXP/FXB presets into synths such as Obxd and Extent Of The Jam's
DigitsVST. Lots of movement on the DAW front, with updated offerings
from Renoise, Mixbus, and Tracktion.
Good times for Linux-based musicians.
Best,
dp