Spotify, the crazy popular Swedish music startup only available in Europe, gave 90% of its users some bad news today. The nine million subscribers to Spotify's free service must either upgrade to a paid plan or enjoy half as much music each month. Slashing the free listening allowance from 20 to 10 hours per month and limiting free users to only five plays per song, Spotify hopes the new restrictions will convert more people to their paid plans. Starting on May 1, the service tweak will take six months to affect users. And their user interface designer is a "sad panda" about it.

What will this mean for Spotify's long-awaited yet still unannounced U.S. launch? In the short term, a lot of angry users saying mean things about the company on the internet. The first comment on Spotify's annoucement blog post is telling: "So long Spotify. It was nice knowing you. Guess I'll go back to pirating music again then."

The Wall Street Journal quotes one soon-to-be-former Spotify user who was ready to abandon the service altogether rather than pay for the features he admittedly loves:

Ah well, it was nice while it lasted. That’s me over to Grooveshark/YouTube/piracy. Which is a shame, because Spotify had by far the best features and interface. I’ll miss the sharing and the ease of making playlists, I had things nicely organised. Thanks for destroying a community of music lovers. Goodbye.

Other free, increasingly feature-rich services stand to gain a lot of users out of the deal. The Next Web points its readers to six alternatives to Spotify, but you probably dont' need to look any further than Grooveshark. The American startup relies on its users to upload tracks and streams 50 to 60 million songs a month. Lacking Spotify's the (now even more) restrictive hurdles, Grooveshark is available on most smart phones and can be listened to anywhere in the world.

What's the catch? Grooveshark is kind of illegal, and although they've secured an advertising revenue-sharing deal with one of the big four record labels, they could be shut down at any time. Whether users like it or not, Spotify is securing deals with record companies in the U.S. and in the long run will a more stable, if more expensive option.

It's also worth pointing out that another very popular free music site took a serious nose-dive when they started charging.