The confusion I have is that Amazon give you the MP3 version of CDs in your cloud account. As far as I can tell once you have them you are not breaking copyright by selling the CD and keeping the MP3 files.
Actually in the UK it is illegal (though unlikely to be enforced) to rip CDs to MP3. Under currently legislation copying any copyright material is forbidden for any reason - including making digital backup copies, or ripping to MP3 players. This is particularly clear where any form of copy protection is used - it is technically illegal to own software or hardware that could potentially have the capacity to break copy protection - even if that is not the intention of the software, device or owner. It is a law that assumes guilt rather than innocence - so much for the law.
Effectively Amazon's new scheme means you can buy a CD (often cheaper than MP3 versions anyway, esp. for classical music) and then legally sell the CD still sealed as new and make a profit on the deal. In the meantime Amazon have given you a copy of the album in MP3 format. Have they really thought this through? (I just checked the terms and conditions and it says nothing about the MP3s only being there for the duration of the ownership of the CD - the only condition is if you download the MP3s and then cancel the order they will charge you for the MP3 version). See
http://www.amazon.co...amp;nodeId=201123480The difference with DVD and BluRay with downloadable content is that I think the license says it is for the owner of the DVD or BD - it would therefore not be the same thing. Also to get the download codes you have to open the package to you can't really sell it as new (esp. since the code, advertised on the pack, has been removed or already claimed).
Oddly I didn't ask Amazon for this service - I am not sure the copyright holders are going to be too happy with it either.