Patently Apple are reporting a patent highlighting Apples plans for a Cloud media streaming service. But the article suggests there is something unique about the way the service is to be delivered.
To avoid streaming problems, the media source is partially locally stored. See Patently Apple for their full article.
Given the reports suggesting Apple has done a deal for media streaming with EMI and on brink of other similar deals, this all points to hopefully something imminent, perhaps as early as June at the next Apple Developers Conference.