When it comes to the kernel-side support for this 64-bit ARM architecture, the first pieces landed with the Linux 3.7 kernel. For the Linux 3.8 merge window, there's various improvements and fixes to the ARM64 architecture. The only item to specifically point out though for the general Linux user would be prepatory work for starting to support KVM virtualization on this architecture. There's still more work needed to get the Kernel-based Virtual Machine working for AArch64, but they're making progress and there's still many months until the ARMv8 hardware will actually be shipping.
It was in the Linux 3.7 kernel where ARM landed Xen virtualization support for the newer ARM Cortex-A15 SoCs that support hardware virtualization. To land possibly for Linux 3.8 is KVM virtualization for the Cortex-A15, but this is separate work from the AArch64 enablement.
The ARM64 pull request for the Linux 3.8 kernel can be found on the kernel mailing list.