Story at the following link for anyone who reads German, as well as a photo:
They're calling it the RAGE (a combination of ring and cage). Finkelstein says it aims to combine all the upsides of ring and cage without any of the downsides, although it's nothing particularly innovative - basically, it's just a six-sided ring with a net under the bottom rope to stop fighters from moving out of bounds when grappling on the ground. Doesn't eliminate the problem of fighters falling through the higher ropes though.
They're going to try it out at M-1 Challenge 37 on 9th April, and presumably if it goes well they'll be using it at all their events from now on.