Spotify is coming to the United States, but what is it?

Their website lists an excited an announcement that the music service is coming to the U.S. (no date in mind), along with a few choice quotes from Mark Zuckerberg and Demi Moore (@mrskutcher, in case you forgot) singing praises of Spotify.

Here's what we know:

Spotify is a Swedish-based music streaming service, currently only available in Sweden, Norway, Finland, Britain, France, Spain and the Netherlands. The service allows users to stream millions (literally, 13 million-plus) tracks from their computer, their mobile phone, and even their home audio system.

According to their site, Spotify offers a few different structures: there's a free version, which simply allows users to stream songs instantly, but it looks like there may be a limit to home many times one could stream a song. There are also two paid versions, Unlimited and Premium, which both offer no ads. Premium also lets users stream direct from their mobile phone, and has an "offline mode for playlists."

No word yet no how much either pay version will cost monthly, or when this service will even be available in the U.S., but it's going to be "soon"!

Some believe that Spotify presents a direct challenge to Apple's iTunes, because of a recent application that allows Spotify users to synchronize songs purchased through iTunes. Steve Jobs and Co. seem to have things locked down pretty well, so it's hard to say whether Spotify will actually throw things off for the massive music company.

Wonder how bands get paid for having their songs on Spotify? No one seems to be talking about that yet, either.