The Linux 3.7 kernel will feature support for the ARM 64-bit architecture (ARM64), which is officially known as AArch64.
The Linux 3.6 kernel is one day old but there's already lots of interesting ARM work happening for 3.7. ARM Xen virtualization support is going into the Linux 3.7 kernel, per the pull request this morning that Konrad has accepted as the Xen kernel maintainer, and now we have AArch64.
ARM originally published the Linux kernel port of AArch64 back in July and since then they have been revising this ARM 64-bit architecture support for the Linux kernel. The work has been ongoing but now with the Linux 3.7 kernel it will be part of the mainline tree.