I recently received and email from guitarist Fernando Perez. His work adapting the music from all over the world to the guitar is very interesting, but not in the usual Guitar Moderne wheelhouse. More relevant is his microtonal work, and his collaboration with luthier Jose de Prados on a guitar with interchangeable fretboards, allowing you to instantly switch from a standard fret system, to fretless or any microtonal system you choose. There have been and are others venturing into this field, especially in the microtonal field but Perez and Prados appear to have come up with something workable.
Also a nice introduction to other microtonal guitar solutions: