aren't you supposed to get a boost when people talk about your "brand" these days? i dont think it has to be an actual link anymore. even straight text will do, if google can recognise that its definitely your site they're talking about.
voucherdigg (all one word) is all over the net at the moment. presumably that is enough to turn it into a "brand", regardless of how many actual links he gets.
i can understand how google can devalue backlinks (because they might look spammy, paid for, or automated). but devaluing a conversation must be a lot harder.