Besides the recently published AArch64 support for the Linux kernel, developers with ARM Holdings have also been tackling the compiler support and other areas of the Linux toolchain.
Right now within the GNU Compiler Collection (GCC) there is an "AArch64" branch that provides the initial ARMv8 64-bit compiler support. In recent days, including today, more ARM patches have been committed as can be seen from the gcc-patches mailing list.
Aside from the GCC support for this next-generation ARM architecture, I have yet to see any LLVM support yet for ARMv8. However, with time it's inevitable that there will be AArch64 support there too within the compiler infrastructure that provides the basis for Clang.
Last week at DebConf Managua, Steve McIntyre of ARM shared that more code/documentation should be coming soon along with other ARMv8 Linux work. The Debian project is planning for their ARMv8 release in "Wheezy + 1" although Ubuntu will likely publish a release much sooner.
The first shipping hardware based upon ARMv8 will likely happen sometime early next calendar year.