http://blog.vervestudios.co/blog/post/2011/05/13/IE9-Only-CSS-Hack.aspx
#element {
color:orange;
}
#element {
*color: white; /* IE6+7, doesn't work in IE8/9 as IE7 */
}
#element {
_color: red; /* IE6 */
}
#element {
color: green\0/IE8+9; /* IE8+9 */
}
:root #element { color:pink \0/IE9; } /* IE9 */