The Vulkan API, announced during the Game Developers Conference last March, is a low-level method to communicate with GPUs. It is essentially a fork of AMD's Mantle, which was modified to include things like OpenCL's SPIR bytecode for its shading and compute language, rather than DirectX and Mantle's HLSL (or OpenGL's GLSL). At the time, Khronos mentioned that Vulkan is expected to be released in 2015, and that they intend to “under promise and over deliver” on that schedule. Being November, I expect that something came up, which isn't too surprising as Microsoft seems to have similar issues with DirectX 12.
That said, Basemark has just announced that they will have (at least one?) Vulkan-compatible benchmark available in Q2 2016. It is unclear whether they mean calendar year or some arbitrary fiscal year. Basemark GPU Vulkan is planned to focus on “relevant Vulkan API performance tests as opposed to theoretical workloads”. This sounds like more than a high-draw, low detail technical demo, which is an interesting metric, but one that will probably be covered elsewhere (like the competing 3DMark from Futuremark).
Hopefully the roll-out, for developers at the very least, will occur this year, though.