Frustratingly, Mini DisplayPort doesn’t include audio, so to get sound when outputting to an HDTV using HDMI, you’d need to use yet another cable. This adapter uses USB for audio, so you get the full A/V with just one cable.
As someone who’s had trouble with Mac Mini audio output before, this is a much welcome addition. At least when it arrives in August. And honestly, I don’t care what the price is.