Short answer is: No.
I'll put the long answer together when I have the time. But its just that developing GPU renderer is much more difficult and the result can be fairly limited (supported materials, texmaps, fakes, memory limitations). GPU rendering would not plug well into Corona architecture at all.
And also there is no clear indication that GPU rendering is faster. Yes, there are some prototype ultra-fast ray tracers on GPU, but there were ultra-fast CPU ray tracers on Pentium 3 that reported comparable performance to Embree on quadcore i7. Both intel and nvidia have provided their promotional ray tracers, one on CPU (embree with crown scene), the other on GPU (design garage). I've tested embree on i7 and Design Garage on gf580GTX, and I have to say, I was much more impressed with embree, regarding the speed to scene difficulty ratio.
