I am currently testing wmii, which is a new style window manager. What I havent seen before is some arguments about WIMP desktops. I do not think its really matured – also because to be really non WIMP there need to be the applications that support this new metaphor must be invented.
One question is if non WIMP means non graphical? For wmii there are some command line tools like the ii irc client. I think that it would be possible to create a desktop that id graphical and non WIMP. Its only currently that the only non WIMP tools are command line.