Spotify is about to start offering Facebook-style apps and open its app platform to developers, according to The Wall Street Journal.

"When it starts on Wednesday, the "app finder" is likely to include reviews from magazines and blogs that allow users to listen to albums as they read reviews, the people say," the article states. "One app will display lyrics as a song plays, while another will generate a list of upcoming concerts by artists in a user's Spotify playlists and offer links to buy tickets."

As The Verge notes, Spotify has tried to appeal to developers in the past by offering the libspotify set of APIs to integrate Spotify music into other apps.

Leading up to the "What's Next for Spotify" event, digerati threw around ideas of an MP3 store and a full-service iPad app. The event kicks off at 11:45am ET today.

Earlier this month, Spotify revealed that is has 2.5M paying subscribers and Facebook announced that Spotify added 4M additional users since launching the open graph at f8. In a recent Mashable report, Spotify is on track to hit 100M users, based on a job offer post.

Spotify's biggest update came at Facebook's f8 event in September, when the company launched its super-tight integration with Facebook and began requiring all Spotify users to have a Facebook account. Shortly after that, Spotify made it easier to control music sharing on Facebook. It now also lets users see friends' playlists on its mobile apps.

A few weeks ago, Facebook announced that Spotify had added 4M users overall thanks to Facebook. Sean Parker, of Napster and Facebook fame, is a Spotify investor who has described Spotify as a "hyper-efficient system" and the answer to music piracy.

Beyond Pandora, Spotify is competing with cloud-based services. Last week, Google Music launched to let users upload up to 20K songs available for streaming from most devices. That same week, Apple launched iTunes Match, its cloud-based matching and "streaming" service, at $24.95 per year.

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