That's a ventral (upside down) view of a fresh brain before processing at the Allen Institute. The folks there are engaged in an impressive project ("Allen Brain Atlas") to map the entire brain with all its individual neurons so as to aid future neurological research. Call it a "Neural Genome" if you like. It's due for completion in 2012, after which it is expected that the constructions of our neural networks will be discovered, analysed and explained.
Fresh brains have to be collected soon after the donor's death, else nucleic acids beging to work and dissolve the cell membranes. Researchers have a limited window in which to cut the brain into slices and photograph each of them before and quickly packing them away in ice for storage before future RNA analysis.
Read Jonah Lehrer's article at Wired, and view the full gallery of images.