I'm writing this because its an idea I've written about before but I just want to make sure that if there is some idiot or idiot company out there who tries to patent this then I've already written it down in a way that is internationally accessible so arguably could be considered as prior art.
Amazon's Kindle store is a bit like this already in that the purchases that you own are held by Amazon for syncing to multiple devices from their cloud but this doesn't go far enough hence the idea... bloody obvious in my mind but that hasn't stopped people previously applying for patents.
When you buy something from either a physical or virtual channel it comes with a form of identified (e.g. DVDs and CDs have identifying information which can be used to uniquely identify its content independently of that content... its a title of the CD in other words) this identifier can then be looked up in a database to prove that you own the content whether via a physical channel purchase or a virtual store....
Now for the cloud bit....
The cloud service holds the identifiers to which you have content access rights and provides you with future access to that information and the associated content from any device which you own or have access rights to. The cloud service provides a library of approved content from the original distributor and copyright owner. The access identifiers that are purchased (by physical or virtual channel) then act as access tokens to this library and enable the information to be copied to devices that you own and streamed to those that you use.
This service therefore provides a single copy of each file rather than a file per user and maintains the access to that information and content.
Or put it simply, its like having iTunes remember what you have bought and allowing you to download it all again with the added advantage of it recognising that you have already bought a specific CD in the real world and allowing you to download the digital version because you have registered your ownership of the CD via iTunes.
This is for me an obvious addition to MobileMe for Apple and the sort of thing that Amazon, Google or Microsoft could also do. It is also the sort of thing that the record industry should do as it would provide them with a degree of control while providing obvious benefits to consumers.
I don't want to patent this and I don't think software and architectural elements should be patentable... so this is prior art.