What the app does is allow users to listen to songs that are trending on Twitter and then gives the user the ability to add those songs to a playlist. The app is on the Spotify desktop.
A quick peek at the app on Spotify shows that the app might not be all the up to speed. Currently, the app is only showing one featured artist—Wolf and Cub. Once you click on the artist, you're apparently taken to their artist page within Twitter #Music. However, we only got the load page that sadly didn't seem to be loading at all.
Other sites, such as CNET were able to get the app to load fully with a full list of selected genres, and with macklemore as their featured artist. Update: After about 10 more minutes and a refresh, the app started showing for us.
Evolver.fm notes that Twitter pulls songs and mud from the #nowplaying tag on Twitter and blogs and puts those results into five categories: Superstars, Popular, Emerging, Unearthed and Hunted.
Hopefully, the slowness is due to the increased interest in the app, and not due to bugs. Either way, we hope Twitter gets the issue figured out before it could hurt their foray into music.
Twitter just recently announced that they will be taking the company public. The Spotify app is another way the social media platform can attempt to gain revenue through advertising and through the partnership with Spotify itself.