Close
Safari ( well, my nighlies of Webkit from last month ) loads the progressive JPG like a standard JPG. Then color wise, the ICC profile is loaded, and look the same as in Photoshop or Firefox 3 with color management for ICC.

ICC profile is useful when you get file from a scanner or a camera since there are different setting for each of them. It allows to display the image evenly on any OS / software / hardware. But from my experience it's quite bothersome because some software doesn't support them natively, so what you see in Photoshop is not what some other people will see...