Update (10/16/2012)

Version 2.3.2 on either Lion 10.7.5 or Mountain Lion 10.8.2 now supports OpenCL rendering using the Nvidia GT 650M GPU. This runs 5.5X faster than rendering with the CPU. (measured on Retina Macbook Pro on Mountain Lion 10.8.2)

Using CUDA rendering, on a non-sandboxed app (on Mac Lion), the GPU rendering performance is the best yet seen on Macs.

The CUDA render runs 7.2X faster than the OpenCL render on the Intel CPU on a Macbook Pro 2012.

OpenCL rendering on Intel CPU is 38% faster compared to last years 2011 Macbook Pro. CUDA rendering on Nvidia GT 650M is 2.78X faster than OpenCL rendering on ATI 6750M with last year’s 2011 Macbook Pro.

OpenCL rendering on Intel CPU (Macbook Pro 2012) is 2.6x slower than OpenCL rendering on ATI 6750M (Macbook Pro 2011).

On Mac Lion, you have to have a non-sandboxed app to run CUDA. Apps on the Mac App store have to be sandboxed and can’t run CUDA.