POWER8 is IBM's upcoming architecture and new CPUs that will should be introduced in 2013 and the processors will be packing more cores, more accelerators, larger cache sizes, improved reliability, and the fourth-generation Simultaneous Multi-Threading (SMT). POWER8 should be much faster than the current-generation POWER7 / POWER7+ processors.
Among the POWER8 changes being merged as part of PowerPC 3.8 pull is all of the initial CPU setup code, the cputable entry, and various other bits for hardware enablement. However, support for some POWER8 items like transactional memory will not be landing until the Linux 3.9 kernel.
More details can be found from the PowerPC pull request.