As far as I can tell, it's powered by an NVIDIA Quadro 6000 workstation. Not sure about the software, but it's likely custom-tweaked.
Perceptive Pixel's tech was originally developed for military applications (and the military does use their displays), but you can see why newsrooms would swoon over tech like this — especially for election coverage.
Here are a few links to related articles that might provide you with more information:
Wikipedia article on Multi-Touch Collaboration Wall:
Perceptive Pixel's page on their 82" display:
NVIDIA's Quadro 6000 page:
2008 WaPo article on CNN's Magic Wall:
Jeff Han TED Talk from 2006: