When the marble cladding was first removed on the night of October 26, an initial inspection by the conservation team from the National Technical University of Athens showed only a layer of fill material underneath. However, as researchers continued their non-stop work over the course of 60 hours, another marble slab with a cross carved into its surface was exposed. By Friday night, just hours before the tomb was to be re-sealed, the original limestone burial bed was revealed intact.The article includes a lot of background information on the site and its archaeological context, so read it all. The restoration work on the Holy Sepulcher (Holy Sepulchre) continues. Background here and links.
"I'm absolutely amazed. My knees are shaking a little bit because I wasn't expecting this,” said Fredrik Hiebert, National Geographic's archaeologist-in-residence. "We can't say 100 percent, but it appears to be visible proof that the location of the tomb has not shifted through time, something that scientists and historians have wondered for decades."
In addition, researchers confirmed the existence of the original limestone cave walls within the 18th-century Edicule, or shrine, which encloses the tomb. A transparent window has been cut into the southern interior wall of the shrine to expose one of the cave walls.
UPDATE: David Meadows has additional background over at Rogue Classicism: Jesus’ ‘Tomb’ in the Church of the Holy Sepulchre: Some Background.