Does Mavericks support OpenCL? I installed the new OS X Mavericks and new Xcode on the "mid 2011" Macbook air.

I run the code from this question, trying to test if the GPU supports OpenCL. But It seems to behave the same it behaved on Mountain Lion. It seems Mavericks doesn't support OpenCL yet.
Mavericks supports OpenCL but your GPU is not compatible (there are no OpenCL drivers for it).

Try running the example with CL_DEVICE_TYPE_CPU, Simply set the variable gpu to 0;

int gpu = 0;


This paper says OpenCL Support on Sandy Bridge is limited: 


  3rd Generation Intel® Core™ Processors with the Intel® HD Graphics 4000/2500


Your Macbook Air is equipped with HD Graphics 3000.