Spotify was the buzz in 2011. Part of why the buzz has tapered is merely time passing, but part of the drop in that buzz was that it closed off to non-premium users after a 6 months trial membership. Millions of people opted to discontinue using Spotify instead of signing up.
The free service of Spotify is funded by advertising. Now that Spotify is reopening its free service back up to people who do not want to pay its user base will swell. It is also possible that its ranks may swell because of increase in buzz surrounding the music player.
This is important for the social media agency because of the advertising. The desktop player supports ads on it, and there are occasional audio ads that play in between tracks. As more and more people use the free service, then the reach of those ads expands. Because of user profiles and possibly some geo-location uses Spotify can also deliver ads that are targeted to location and user demographics.
Spotify is also an excellent data accumulation tool. It can collect and aggregate data about who listens to music online and what they like. IT can also collect data about the ads and who clicks them and when. Overall Spotify could also be in the data business and participating in that campaign can be a tremendous asset to the social media agency.