HD Music downloads have been around for quite a bit. Gimell, Linn, Lindberg Lyd, Naim, etc. have all been selling these for sometime.
More mainstream recordings are getting into the fray with HD Tracks. They generally are of better quality than prevailing consumer formats (especially studio master files from Lindberg Lyd), but as with SACD and DVD-A, some mixes are just bad (and you don't need a high resolution recording to tell those). I've actually had the worst luck with HD Tracks (in terms of distribution file quality), but they have the widest selection and they do have good customer service.