If by "modernization" you mean porting GNOME, then no. Nobody is doing that. Thank God.
In short, my view is that chording your way through rio using a three-button mouse is about as unfriendly as modern Gnome, and that someone ought to put a stop to that without such tomfoolery as porting another DE to Plan9.
Technological modernization won't win Plan9 new supporters, whereas UX modernization will, at worst, make it easier to use.
Edited to add: I have Acme running via plan9ports on the Mac, and even the simple addition of Cmd+C/V/etc. for copy/paste made a world of difference. I am positively thrilled with the notion of actually using it someday without constant fiddling with the Option key and my touchpad.
Admittedly I only use plan 9 for text processing and as a terminal to other (both plan 9 and unix) systems, but I cannot imagine any work toward buttonless-touchpad convenience that would do anything but cripple what is currently a powerful interface.
I'm not sure there's anything to be gained from forcing different paradigms to bend to whatever monoculture is currently in power.