David Kanter from Real World Technologies has taken an indepth look at ARM's new 64-bit architecture, you can learn about it over here.
Last year, ARM announced the 64-bit ARMv8 for Application processors. The new architecture is elegant, backwards compatible, and removes several crufty features from the existing ARMv7. Applied Micro simultaneously demonstrated an FPGA implementation of X-Gene, a custom 64-bit server processor based on ARMv8 that is expected in 2013. Applied Micro and others such as Microsoft helped ARM to define and shape the new architecture. More recently, Samsung and Cavium Networks have both taken architectural licenses and along with start up Calxeda, are expected to produce ARM-based server processors. As an aside, it is quite possible that ARM has developed an additional server profile, or these companies could be using the A-profile..