I gave the Wikipedia article a shot and put in two sentences, along with a network software stub tag and the software infobox. I'd love to add more, but I don't know a whole lot more about the software than is present in the article at the moment. Here's the link: http://en.wikipedia.org/wiki/Mumble_%28computer_software%29
One thing I want to get straightened out, though, is the license for the Mumble logo. I set it to "unknown" until slicer can get that cleared up.