Chalk up a much-needed victory for RealNetworks in its long-awaited foray onto Apple's iPhone. The Seattle company's joint venture with MTV Networks has won approval to offer its Rhapsody subscription-based music service through a new app on the iPhone and iPod touch.

Rhapsody America is expected to start offering the app for download Thursday on the App Store. The app itself is free, but requires a $14.99-a-month Rhapsody To Go subscription to use. However, the company is offering a seven-day free trial period, hoping to encourage new users to give the service a try.

By letting users select any song or album from its catalog of 8 million tracks, the Rhapsody app differs from free services such as Pandora that build automated playlists within a certain genre or related to a certain artist. Rhapsody also offers the ability to browse and select from music charts and preset playlists, but the ability to create custom playlists and select any song or album could help set it apart on the iPhone.

In that way, it will serve as a test of the broader appeal of subscription-based music services.

The situation had the potential for controversy because Rhapsody might have been perceived as competitive with the iPhone's built-in iPod functionality. In addition, RealNetworks has had a contentious history with Apple over the Seattle company's efforts to make its files compatible with the iPod in the past.

Rhapsody took the unusual step of announcing in advance that it had submitted the app for approval, perhaps hoping to take advantage of questions about Apple's lack of approval of the Google Voice app for the iPhone, which was similarly perceived as potentially competitive with native iPhone capabilities.

RealNetworks says it's working to bring Rhapsody to additional platforms later this year.

Here's a screenshot of the welcome screen on the Rhapsody app. Stay tuned for more.

(Post updated at 8:20 with additional details.)