The IEEE Solid State Circuits Society has posted and archive of the talk Exascale Computing--fact or fiction? by Intel fellow Shekhar Borkar. It was a very good talk and covered the technical challenges that are on the road to exascale computing. This includes compute function, memory, interconnect, resiliency, and software. A teraflop system requires ~1kW of power today, and a exascale system would consume 20 MW so power scaling is a major challenge, for example.