It's ARMv8
According to http://raspi.tv/ the CPU is a ARM Cortex A53 CPU
A look on ARMs own site (linked from the above page) and...
The ARM ARMv8-A Cortex-A53 processor offers a balance between performance and power-efficiency and is capable of seamlessly supporting 32-bit and 64-bit code.
Biting the hand that feeds IT
