I actually assume this would certainly be a protection concern if you can see it with JS or Flash. In fact, neither JS or Flash should not supply accessibility to any kind of information of the customer is COMPUTER other than some really standard information concerning the OS, internet browser, screen resolution and also such, points that you would in fact require on a regular basis. That recognizes, could be feasible with IE6: D
The MAC address is most definitely not something you can survive an internet site unless a bug exists.
If you can get people MAC address you can transform you possess via some hardware/software methods and also hence make your computer system resemble their own which is a really negative point for security!