this article, this is NOT javascript that is getting the MAC address. the script is loading an activeX, which is not part of javascript or html. it is basically a piece of software that runs on your local machine the same as an executable would.
what happens is when your browser loads that page is it DOWNLOADS the activeX program to your local, your computer then RUNS the activeX which gets your MAC addy and then sends the MAC address BACK to the site.
it is not a case of the website's code grabbing your MAC address, because this is not possible through pure html or javascript code, and it never will be. because of privacy issues and technological issues, such as, even if there was code to grab the mac address through code, it would grab the mac address of the last router that was passed through before connecting to that website, and not the mac address of your pc.
activeX goes around that, because it loads as a software on your local and is then able to get the MAC address directly without having any networking involved, and then sends the info over the net.
Point is, disable activeX or use a browser that doesnt use them like firefox, and your mac and any other info not obtainable through pure javascript and html is safe