Firefix is now enabling icc support by default in their new beta! See this page. This is great news
The default settings only enable color correction for tagged images, just like Safari does. You can enable full color management in a similar way as before. There is now a "gfx.color_management.mode" variable in the about:config box that you set to 1 in order to also manage untagged images and CSS colors as if they are sRGB. This is very helpful for folks with wide gamut displays. IE as always is far behind in this field.
To be complete: Here is a link showing how to enable color management in the current Firefox release. Doing this indeed color manages even untagged images. A very important feature.