BBC has an interesting story and a wonderful graphic showing the top 500 supercomputers in the world by country. Story is here.
Although the USA still leads in Supercomputing superpower, China is rising fast with two of the top ten fastest machines, and appears to be looking to become a major and key player in this area.
Supercomputers are used in many applications that require massive computational speed and power, among them Climate Research, Military Applications such as nuclear bomb simulations, and – arguably by far the most interesting – Artificial Intelligence research and development. My understanding is that IBM Blue Genes are currently the fastest machines doing AI but hopefully the US based Jaguar – a Cray machine at Oak Ridge Labs and the world’s fastest computer at 1.8 peta FLOPS, will soon be tasked with AI research.