Satellite-radio service provider XM Radio is set to launch a high-definition (HD) version of its service called XM Radio HD Surround. This new offering will provide 5.1 channels of surround sound, and will be accompanied by special channels that output only in surround sound. Naturally, you'll need new XM-compatible hardware to receive the XM Radio HD Surround content, but a variety of hardware makers will show up with new gear. Given that most satellite-radio content today is notable only for its tinny-ness, it's interesting to see XM making such a huge leap ahead in audio quality. I'm sure that will make up for the fact that Howard Stern went to Sirius.