This email from the owner of the website explains:
Gliocast is a set of software tools for visualizing fiber tracts. The emphasis is on the 3D display technologies. Gliocast includes a rudimentary model for tumor growth, but more physically realistic models can be substituted for it.
Fiber tract imagery provided by the Banks Laboratory at the University of Tennessee.
Brain dataset courtesy of Gordon Kindlmann at the Scientific Computing and Imaging Institute, University of Utah, and Andrew Alexander, W. M. Keck Laboratory for Functional Brain Imaging and Behavior, University of Wisconsin-Madison.
Update: On a related note, Senator Ted Kennedy's malignant glioma, which was diagnosed about two weeks ago, has just been successfully removed by neurosurgeons at Duke University Medical School.
Wow. Interesting and yet so staggeringly scary.