Concurrency / Parallel Computation
Processors are no longer getting significantly faster, just more numerous. Knowing how to take advantage of multi-core machines and computing clusters is going to be a valuable skill.
There is an alphabet soup of technologies out there: AMP, SMP, MPP, NUMA, GPGU, CUDA, OpenCL, etc. Effective programmers will have to be conversant in these, plus thread saftey, synchronization mechanizms, cache interactions, and more.
Let's have some help figuring out how to turn our serial processes into parallel ones.