I have this slideshow with a overlay that pops up on hover, you can view it here. Just hover over any pictures below the 'featured' section. Works great in FF, Webkit, IE9. I made a separate stylesheet for less than IE9 and in it I have declared width, height, zoom, positioning, used all the filters that work in IE.... and I'm not getting opacity in either IE7 or IE8. The div with class overlay is appended with JQuery, is this a problem? Here is my css:
.overlay {
background-color:#fff;
filter:alpha(opacity=60);
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=60)";
filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=65);
zoom:1;
width:160px;
height:20px;
z-index:50;
position:absolute;
bottom:0;
}