In theory, making a GUI shell to run with DF is entirely possible. The question isn't whether we can do it, though, but whether we should.
1) Many of the menus can't be read or interpreted, at least not without an extensive expansion of DFhack. Thus, much of the game information can't be reported.
2) Tarn has expressed specific reservations about this sort of thing, and for good reason. We can't match pace with his development, and it takes a significant ammount of time and effort to update DFHack, and Stonesense, for each new release. A lot of things change behind the scenes with each release.
3) Assuming that this hypothetical GUI would be pretty, shiney, and more user-friendly, Players may come to regard it as the "proper" interface for DF, which it is not. This could potentially harm Tarn's development process, and/or his drive to work on things... especially since he doesn't want this to evolve into anything resembling a collaboration. Personally, I can understand his perspective, and really don't want that to happen, because he's putting a lot into this.
It's been discussed before. I think that theoretically it would be a nice idea, but unless Tarn were to give an explicit "Go Ahead," I would personally not feel comfortable having my work used in such a program.
EDIT: Speaking of my work, guys... ermmm... would Japa or Jonas or Peter or whoever care to direct me toward what graphical assets y'all need? I think I've sabatacled long enough, and I seem to have lost my old list. >.<;