No new fancy cable boxes are necessary for this upgrade. However, it is contingent on the home viewer having both the RealD glasses (have you snuck a pair home yet?) and a 3D-enabled television. What that means is a television that can handle two simultaneous video input signals. (Old-school models just won't do.) RealD technology is a new twist on old-school stereoscopy, where two images held away from a special pair of glasses would make cool retro images pop into the third dimension. Special cameras captures two images that simulate the different perspectives of the left and right eye, and they're brought together for an extra-dimensional experience.
So, if you have the saucy, 3D compatible TV and a pair or two of RealD glasses, the third dimension is all yours.