Just in case anyone is crawling SO for an answer to this, the above two answers aren’t solving the core problem which is answered here – CSS media query not working in IE 9
Basically inline CSS3 media queries DO work in IE9 but you have to disable Compatibilty mode –
<meta http-equiv="X-UA-Compatible" content="IE=9">
The above meta tag needs to be placed before any other meta tags otherwise IE9 will default to compatibility mode on and will subsequently not work.