Just in time for those six months of free unlimited streaming subscriptions to expire, Spotify has a big announcement this afternoon. When Spotify launched in the U.S. last July, to hook users it offered a free service alongside its paid options. With the gratis offering uers got access to all 15 million to Spotify's streaming library, with no monthly or hourly caps, and few ads all for zero dollars. The only catch: The set-up only lasts for six months, after which hours get capped at a measly 10 hours, or users can pay the $4.99 or $9.99 per month fees. With just a month and a half before those who rushed to sign up for those free six months are asked to pony up cash, Spotify's got to impress now. Hence the press conference.

As of now, Spotify doesn't have that many benefits over other streaming music services. RdioMOG, Grooveshark: They all have free streaming options. The libraries are all about the size of Spotify's 11 million strong, at 11, 13 and 7 million respectively, it's not a huge downgrade.* Beyond song choice, Spotify does have Facebook integration, but for some that's a deterrent rather than a  perk. Other than that, it has this free thing going for it.  When the service first went live state-side it attracted 1.4 million freeloading subscribers. Of course, some suckers paid up to get the service on their phones or to avoid doing it later -- at least 400,000 as of mid-September. But what happens when Spotify takes away its free-unlimited streaming? As of now, the service isn't worth paying for, when users can get free basically unlimited streaming at Pandora or Rdio. Granted MOG, Rdio and Pandora all have caps, but nothing as strict as 10 hours per month. 

Spotify's hoping to impress its curious but unwilling to pay customers at this afternoon's press conference with extras that don't exactly make up for the lost freedom. The "big announcement" includes an app store addition, reports The Wall Street Journal's Ethan Smith. While listening to music, apps would "enhance" the experience adding music reviews or lyrics alongside songs. In addition to apps, the streaming music service will also announce "deeper integration" with Sonos music systems and based off total speculation, CNET guesses the service could reveal a music download store. Even if all these things are true, is any of that worth $4.99 a month to you? 

Update 12:44 p.m.: Exactly as expected, Spotify has announced an API for developers to create HTML 5 apps for the service. For example, CEO Daniel Ek demonstrated a Rolling Stone app where he read a song review in Spotify while listening to that very track. More apps to come as soon as developers start making them. The platform is open to all developers and apps will make it onto the streaming service with permission from Spotify. 

This post originally stated that Spotify has a 15 million song library in the U.S. and that MOG had an 11 million song library.