This paper appeared in Nature this week, but the authors have uploaded it to ArXiv and it appeared today. Using STM/STS technique, they were able to obtained the spectroscopy in both real and momentum space as a function of doping along the nodal direction of the Fermi surface of a high-Tc superconductor. The results show that as the compound approaches the Mott insulating phase, the mobile Bogoliubov quasiparticles from the Cooper pairs are slowly being replaced by the localized electrons.
A first-rate experiment!
Edit: A BNL press release on this work can be found here.