But the first-sale doctrine only applies to tangible goods, such as CDs. Digital music downloads (just like movies and TV shows and books) come with a completely different, much more limited set of rights. If you buy a digital album from an online service such as the iTunes store, Amazon MP3, or eMusic, you have no legal right to lend that album to a friend, as you could if you had purchased a CD. If you decide after a few listens that you hate the album, well, tough. You can’t resell it. You can’t even legally give it away.
That applies to the US, digital products fall into a grey area of the Sale of Goods Act in the UK. Professor Robert Bradgate has written an interesting paper for the UK Department for Business, Innovation and Skills (PDF) on the subject.
The article actually brings up an interesting second point, which is the terms and conditions we're signing up to, do you read them? I don't. The iTunes Store terms are 14,000 words of legalese. Who can ever be expected to read that? We need some legislation to limit the length and summarise them for the lay person the same way banking and mortgages have been forced to use clear language.