The Wall Street Journal is reporting this evening that Apple is working on a streaming music service that would put it head-to-head with the likes of Pandora. Though this is a rumor that has come up several times over the past few years, there might be no better time to do it: the next iPhone, being announced next week, is widely assumed to incorporate LTE, which would allow such a service to stream at high quality and without interruption (WSJ also says it'll work on Mac, presumably through iTunes). In fact, the report points out that Apple abandoned such plans in the past due to prohibitive licensing costs, opting to build iTunes Genius instead.

Regarding its latest effort, Apple is said to be negotiating slightly different licenses for the music than Pandora uses because it wants a higher degree of user interactivity — Pandora places a variety of restrictions on how users can choose and skip through songs, so Apple may be gunning for something that straddles the border between Pandora and full-on subscription services like Spotify and Rdio, though it would use its iAd platform to intersperse product placements between tracks.

There's no set launch date — which probably hinges on successful license negotiations, among other things — though Apple's iPhone event is scheduled for next Wednesday, and WSJ says that the service could take "months" to roll out.