RealNetworks is getting ready to submit for Apple's approval a long-rumored Rhapsody app for the iPhone, as the Seattle-based company looks to expand its music subscription service to more devices. The big question: Will the app make it through the approval process?

Neil Smith, vice president of business management for Rhapsody, tells the New York Times in a post this morning that he believes Apple will approve the app, although he hasn't received any explicit confirmation of that fact from the Cupertino, Calif., company.

The question is significant because Rhapsody could be 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. The situation will be watched closely in the industry because of the recent wrangling over the Google Voice app for the iPhone.

A native music subscription service has long been absent from the iPod, even as Microsoft, RealNetworks and other have offered theirs via competing devices. RealNetworks and joint venture partner MTV Networks offer Rhapsody for a $14.99 monthly subscription, giving them unlimited access to songs of their choice Existing music services on the iPhone and iPod touch, such as Pandora, don't give users the ability to select individual songs -- instead creating virtual "stations" that play songs within a certain genre or category of artist.

Update: Lacy Kemp offers more details on the official RealNetworks blog.

"Subscribers can just log in to the app with their existing user name and password and the experience will be seamless. Non-subscribers will have the opportunity to try the app for a limited time free-trial period," Kemp writes, adding, "We are working diligently on an Android app and once we’re done there, we plan to turn our sights on more mobile platform and carrier app stores."