It all depends on the hardware you have and the OS.

I've found Guiminer for MacOSX works with OpenCL on my CPU, OSX 10.8.4 and GPU currently, but I don't have an ASIC yet (BFL 5 GH USB on order). Apparently Asteroid.app (also MacOSX) will work with cgminer on my GPU and the ASIC once it gets here.

I run a 2007 Mac Mini and steady pull about 3-4 MH/s with OpenCL. Asteroid.app runs well on 10.8.4, but lags the GPU and only gets 600 kH/s. Once the ASIC gets here, I'll have to find the best mix, but my guess is that Asteroid.app will get the nod only for the ASIC, with Guiminer running the CPU-GPU combo.

Jarl

Refrences:

Asteroid.app
Website: www.asteroidapp.com
Donate: 18jzhWi8VU3RtDAyEGFCapkftG7haJyhmY

Guiminer
Website: github.com/Kiv/poclbm
Download: http://cloud.github.com/downloads/pletoss/poclbm/guiminer-poclbm-macosx.dmg
Donate: 1MDDh2h4cAZDafgc94mr9q95dhRYcJbNQo