And of course, song length becomes part of what you're paying for. Which is actually pretty logical in terms of overall value...

I suspect there is no direct relationship between the time and effort an artist puts into the recording of a song and the finished song's length. However the music store incurs costs vaguely proportional to file size (encoding, storage, bandwidth). I could easily see a model with a flat fee per song to the artist (and label - they're still gonna get their cut), and variable fees to the store.

A "better" song will (presumably) be downloaded more, and generate more revenue for the artist and label, and cover their costs. Those willing to pay for higher quailty encodings will generate revenue for the store and cover its costs.

-jk