Another wrench has been thrown into the claim of experimental observation of supersolids. A new paper in PRL is throwing doubt into such observation, and in fact, attribute the apparent observation to quantum plasticity.
Looks like a lot more work needs to be done to verify if we truly have a supersolid in such a system.
 J. D. Reppy Phys. Rev. Lett. 104, 255301 (2010).