The term "Intellectual Property" covers nearly everything I mean by a "message" except patents, and it probably wouldn't be much of a stretch for most intellectual property lawyers to see privacy-sensitive information as another form of intellectual property. (It certainly already is once it's collected, becoming a normal copyrighted aggregation.)
Many people criticize the term "intellectual property" as inherently containing a metaphor of "ownership", be it of the communication itself, of the ideas (patents), of the phrasing (trademarks), or something. They believe that the physical concept of "ownership" does not apply in this domain, because it has no meaning. They believe that using the term "theft" or even worse, "piracy" is inappropriate because there are no real analogues with the physical meanings of the term. By using these terms, the entire conversation about communication is being prejudiced in a certain direction that does not truly reflect how the things referred to as "intellectual property" works.
They are correct. Certain aspects of the "property" idea are still useful, but as a whole, the entire "intellectual property" idea is a bad metaphor that inhibits understanding, rather then helping it. The few good aspects are swamped by the ways the metaphor impedes understanding. Communication is not property. It can not be meaningfully stolen. It can not be meaningfully transferred in toto to someone else, because at a bare minimum, the original owner will still remember the content of the communication. There is no meaningful analog to copying a communication in a physical process.
A metaphor is only as useful as it correlates to the origin of the metaphor. The fatal flaw of the "intellectual property" metaphor is that with communication, possession is divorced from the ability to own rights on the property. I own this physical chair I am sitting in as I write this. I can do as I please with it, and you can not. If I give it to you, I do not have it any more, and I lose all rights to it. On the other hand, I can and have given you a copy of this essay, yet I believe I retain certain rights to it. This is a night-and-day difference between "intellectual property" and real property, much more then enough to make the metaphor useless.
"Intellectual property" as a concept dates from a time when we did not understand how thoroughly computers would revolutionize communication and help us attain nearly 100% of the theoretical capabilities of communication. The fact is, we've outgrown this old metaphor, and we should be mature enough as a species to give up this crutch. Just as we gave up the concept of a "horseless carriage" and moved to "automobile", just as we gave up "wireless telegraph" and moved to "radio", it's time to give up "non-physical property" and moved to a more mature model of communication.
Note throughout this essay I've studiously avoided using the term "intellectual property" unless I was explicitly discussing the current modes of thinking. After all, the whole point of my essay is to clarify thinking, not muddy it up.