Parallel computing demonstrated – Not the best quality, but the other one is >9 minutes long. But GPUs (video chips) are parallel processors not unlike supercomputers, and some actually use video cards instead of CPUs for processing. For instance, those who mine BitCoins usually use a mere mid-range Core i5 CPU driving two of the best video cards the builder can afford.
They run the same programs as normal computers, so they often run C or C++.
However, those languages don’t have the sort of multithreading support that is required when you have thousands of cores, so they are developing new languages to handle it more efficiently. To date, most of those more efficient languages are proprietary nearly to the point of being custom jobs though, so Harlan and Fortress are barely worth mentioning beyond noting that new hardware is prompting a paradigm shift in programming.