Rhapsody is a music streaming service, similar to Napster and Microsoft's Zune Pass. It has a huge catalog of more than 8 million songs and some really terrific Internet radio options. For $15 a month, users can stream as much music as they want. If you have a compatible Rhapsody portable device, you can even take your tunes with you.
Gdgt got an inside look at the Rhapsody app and they were impressed. There's just one problem: the first version of the application will only stream songs, there is no "offline" mode. This is in stark contrast to Spotify's yet-to-be-released iPhone app, which offers similar on-demand tune access, but also has an offline playback mode. According to Real, an offline mode will be added to the 2.0 version of the program.
For that to happen, Rhapsody needs to get approved by Apple first. Although there are plenty of streaming music apps out there (Last.fm, Pandora, Slacker Radio, an the Sirius XM app), those services aren't marketed as a potential direct competitor to iTunes. They don't allow on-demand song access. Using the swelling controversy regarding the App Store approval process to its advantage, Real is making a big splash. The goal, I'm sure, is to have so much publicity surrounding the app for Apple to be unable to reject it.
You can take a look at this video that the Rhapsody team created showing off the application: