http://www.apple.com/itunes/lp-and-extras/ has 'em all. Very cool.
So on the one hand, we have a format based on standards like HTML, CSS, where you essentially write a bunch of Web pages and add some metadata and you're done. There's specifications, there's templates, and there's best practices — all out in the open.
And on the other hand, you have the overengineered, closed, DRM-infested solutions like the CMX format the music industry wants instead.
The catch? Once again, Apple is overly eager to act as a gatekeeper ("Your iTunes LP or iTunes Extras will be reviewed by the iTunes team for appropriateness of content and for technical quality"). And an electronic submission system isn't coming until "the first quarter of 2010". Still, this sounds an awful lot friendlier for both artist and consumer.