Turns out Firefox 3 is ICC-aware! However it ships with color management turned off, so you must enable it. There is a handy little "add-on" for the purpose:
https://addons.mozilla.org/en-US/firefox/addon/6891
In my testing under Windows XP this works very nicely, Supposedly there is a 10-15% performance hit in Firefox, but I do not notice it.
Andrew