Blognosticator blog has a great entry about color management in web browsers.
For a good browser test you should also check out this page at the ICC's site which also tests for ICC v4 compliance. (a new version of the ICC profile format that is slow in being supported)
Color management in web browsers is actually quite a complicated thing. Web browsers are not just image viewers but are much more like InDesign and Quark. They are image and content aggregators (not to mention application platforms). So even though an image may contain a profile and the browser may display it properly, many or all of the other elements on the page may not display properly. In many layouts and designs, incomplete color management is worse than none.
We will continue to research, report and supply solutions to color in the digital display realm, so stay tuned.