How can I scale the content of an iframe?

How can I scale the content of an iframe (in my example it is an HTML page, and is not a popup) in a page of my web site?

For example, I want to display the content that appears in the iframe at 80% of the original size.

Kip's solution should work on Opera and Safari if you change the CSS to:

<style>
    #wrap { width: 600px; height: 390px; padding: 0; overflow: hidden; }
    #frame { width: 800px; height: 520px; border: 1px solid black; }
    #frame {
        -ms-zoom: 0.75;
        -moz-transform: scale(0.75);
        -moz-transform-origin: 0 0;
        -o-transform: scale(0.75);
        -o-transform-origin: 0 0;
        -webkit-transform: scale(0.75);
        -webkit-transform-origin: 0 0;
    }
</style>

You might also want to specify overflow: hidden on #frame to prevent scrollbars.

I found a solution that works in IE and Firefox (at least on the current versions). On Safari/Chrome, the iframe is resized to 75% of its original size, but the content within the iframe is not scaled at all. In Opera, this doesn't seem to work. This feels a bit esoteric, so if there is a better way to do it I'd welcome suggestions.

<style>
#wrap { width: 600px; height: 390px; padding: 0; overflow: hidden; }
#frame { width: 800px; height: 520px; border: 1px solid black; }
#frame { zoom: 0.75; -moz-transform: scale(0.75); -moz-transform-origin: 0 0; }
</style>

...

<p>Some text before the frame</p>
<div id="wrap">
<iframe id="frame" src="test2.html"></iframe>
</div>
<p>Some text after the frame</p>
</body>

Note: I had to use the wrap element for Firefox. For some reason, in Firefox when you scale the object down by 75%, it still uses the original size of the image for layout reasons. (Try removing the div from the sample code above and you'll see what I mean.)

I found some of this from this question.