This is a bizarre case. Former Procol Harum keyboardist Matthew Fisher sued for a share of the copyright to "Whiter Shade of Pale" based on his contribution as keyboardist on the recording and...won. I'm pretty sure that's unprecedented. Studio musicians routinely contribute key melodic hooks to songs for which they receive no copyright interest. It's just part of the gig.
Before I get into my criticism of the decision, I should mention I actually think the court here was aiming at something desirable, namely, rewarding such contributions with some kind of quasi-copyright protection when those contributions effectively become a part of the song. An example that comes to my mind is session guitarist Robert White opening riff to "My Girl", a lick that's so integral to the song you really can't imagine someone covering the song without it. I think most folks would agree that White deserved more thanks for what he contributed than his standard $20 song fee.
That being said, the legal mechanism established in this case is an impossibly blunt instrument to implement this kind of reward. And besides, I doubt anyone thinks even an original contribution like White's would be due a 40 percent share of the copyright (which is what the judge here awarded Fisher). So the court's decision is pretty bad even if you end the criticism there.
But the truly bizarre thing about this case is that Fisher's averred contribution isn't even original. Rather, it's a slightly digested rendition of Bach's Orchestral Suite in D (a/k/a "Air on a G String"). So whether or not it was Fisher's idea to play that melody on the organ on "Pale" is irrelevant: Bach's melody was in the public domain. For whatever reason, this point isn't made in the article, so thought I'd mention it.
BTW, I once did a quasi-surf-guitar version of Bach's "Air." Kind of fun. Just for kicks, I'll upload it to my MySpace jukebox for your listening pleasure and update here when it's ready to spin. Till then...
UPDATE: Okay, surf's up, so cut on over and catch some "Air," dude.