Following up on a question on the users list, I found this blog entry: http://blogs.msdn.com/ie/archive/2006/10/17/accept-language-header-for-internet-explorer-7.aspx which says that IE7 now uses only "language/locale pairs" in the Accept-Language header.
They follow this up with: "If a given server is only interested in the user's language and not the locale, it can ignore the locale portion by simply truncating the code at the first dash." This tells server to ignore RFC2616 section 14.4 if they wish to work with IE7. The effect of this is that users who specify more than one acceptable language in IE7 aren't going to get the one they really prefer in many cases when working with HTTP/1.1 compliant servers (like apache httpd). (If only one language is selected, things should work okay because we added a work-around for this in 2.0. But it is impossible to work-around the problem with multiple languages and still follow the RFC.) It would be possible to add a BrowserMatch-settable variable to do the HTTP-breaking recommended by Microsoft, but I don't know if it is worth it. Joshua.
