Here is what this is about:
Neither Apple's built-in calibration utility, nor Supercal, is creating an ICC profile for your display. It is calibrating the LUT curves, and inserting that LUT table into an existing profile. If you use the Apple calibration utility, it is going to use the default ICC profile for your display. If you use Supercal, it gives you a choice. SRGB is a good all around choice, but it is not really an accurate representation of the gamut of your display.
What it WILL do, however, is neutralize the greyscale for your screen and set your display's gamma and whitepoint. This is a huge improvement vs. an uncalibrated display.
Neither Apple's utility, nor SuperCal is capable of generating a profile that you can use in Photoshop to accurately convert from your displays colorspace to other colorspaces and vice versa. This is impossible to do with a visual calibration, as your eyes do not report LAB values. In order to generate an accurate display profile, and not just an LUT table, you will need third-party software such as Monaco Profiler or Gretag Macbeth ProfileMaker, and a hardware device supported by the software.