Where is my Opacity IE-8?

Was not expecting to hit this issue with IE-8 - Couldn't work out how to make sure my div is transparent. 
Here is the CSS I found from the IE Team blog:

    -moz-opacity:.50;
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
    filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=50);
    opacity:.50;

IE8 CSS 'Active' hover not working

I'm creating a new web-site layout for my company.  We are targeting the latest most standard compliant browsers (IE7 be damned)...

Anyway.  Has anyone else noticed that the CSS action "Active" doesn't work anymore?  It does in FF, Chrome and IE7 compatible mode of IE8.

What happened to here?