Get NAT'ed IP Address Using JS in Firefox

I just read Jeremiah posting regarding how to get NAT'ed IP address using JavaScript in Firefox version 1.5-2.0.

It happens because in Firefox, JavaScript can access Java classes directly (java.net.Socket). You can try it here (copied from Jeremiah's posting) :

When I think about it and how this can be used by the bad guys, I feel very scare. One of the solution for this is by blocking JavaScript from a website. In Firefox, you can use NoScript.