Remember VHS versus Beta? We're at it again with SACD and DVD-A. These audiophile formats are competing for the same market -- the high-end audio listener. SACD is sponsored by Sony (who has a history of pushing its own formats), and DVD-A is an audio format sponsored by the engineering group that developed the DVD format that we use for home video.
The nice thing about this format war is that because the discs each format uses are the same size, some hybrid players can handle both formats. That way, if one format eventually takes over the other, you aren't stuck with a bunch of useless hardware. Also, remember that you need special equipment to play these high-end recordings. You can't take advantage of the additional features that SACD and DVD-A offer if you're only using stereo speakers. The good news is that SACD can play in normal players, albeit at the standard fidelity.