And in the press photos, we do have some idea of the rear suspension--third spring/damper on top of the gearbox casing, orthordox pushrods opening the third spring/damper. Presumably the torsion bars/main shocks are mounted on the side of the gearbox casing, and looks very similar to the orginal 908.
However, I do wonder what the member that attaches to the transmission casing that's between the upper wishbone arms and located behind the pushrod bellcrank is. It's colored the same shade of black powdercoating as the main wishbones, but isn't one of them. Some type of locating member or linkage for the suspension?
http://www.audiworld.com/news/11/r18-engine/
Also, can the rumored Gemini like quick change gearbox be ruled out, as it seems that the suspension--from what little we can make out--is firmly attached to the gearbox casing and uses some modular system to access the internals?