No so much a function as an option...

Problem: You embedd a CDF on a web page but the content is rendered as grey boxes.

Cause: This is a security issue, the same as when you open a notebook with dynamic content from an untrusted path on your computer.

Solution: On your desktop you are asked if you want to enable dynamic content. You press the button and everything in your notebook works. By using the "option" {fullscreen:'true'} an embedded CDF will open in "full screen mode" meaning that the enabled content warning will appear and therefore provide your viewers with the button to enable dynamic content.

Usage:

<script src="http://www.wolfram.com/cdf-player/plugin/v2.1/cdfplugin.js" type="text/javascript">
</script>
<script type="text/javascript">
var cdf = new cdf_plugin();
cdf.embed("http://path.to/myCDF.cdf", 500, 600,{fullscreen:'true'});
</script>