Browser IDN Issues ?

Today as I was searching the net, I came accross a website that has a posting in it about a security issue in many browsers. Including Mozilla's FireFox, which I run myself. And it listed many, many others as well. I was just wondering if anyone had heard of this issue as well? "IDN toggle", is what it is called I guess. Said last night Mozilla had released a patch for FireFox, but I wasn't going to download it untill I spoke with someone who knows more about this stuff than I do.
The website is " www.metafilter.com " , you will find the post half way down the home page. "New FireFox build fixes IDN toggle".
If someone could give me more info on this I would really appreciate that.
Thanks ;-) Carl Tapp