I wanted to get some data on Java's deployment frequency among web readers, and couldn't find any useful published figures from Sun. However, I did find that Sun's investment into Java deployment in terms of better installer can pay off for measurement as well, and that the Deployment Toolkit of Java's next release provides just the kind of tools I could use to augment Google Analytics which has excellent built-in measurement for Flash, but not for Java.

On this site, I found that 31% of visitors have Java 6, 11% have Java 5, 9% the upcoming OpenJDK (hello, Linux readers!), and the rest either no version at all, or some version I'd consider to be so old as to be completely useless. We measured Habbo users as well, and though I will not reveal exact stats of that userbase here, the penetration of Java 6 was significantly higher.

If you wish to repeat this measurement on your own site, you'll want to attach the following scriptlet AFTER your regular Google Analytics measurement tags at the end of your page template. Let me know by comment what you find out!

<script src="http://java.com/js/deployJava.js" type="text/javascript"></script>
<script type="text/javascript">
if (document.cookie.indexOf('; java=') < 0) {
var list = deployJava.getJREs();
var version;
if (list.length == 0) { version='none'; } else { version=list[0]; }
__utmSetVar('java_'+version);
document.cookie = 'java='+escape(version);
}
</script>