To understand the consequences of property customs, it will help us to look at them from yet another angle; that of animal ethology, specifically the ethology of territory.
Property is an abstraction of animal territoriality, which evolved as a way of reducing intra-species violence. By marking his bounds, and respecting the bounds of others, a wolf diminishes his chances of being in a fight which could weaken or kill him and make him less reproductively successful.
Similarly, the function of property in human societies is to prevent inter-human conflict by setting bounds that clearly separate peaceful behavior from aggression. It is sometimes fashionable to describe human property as an arbitrary social convention, but this is dead wrong. Anybody who has ever owned a dog who barked when strangers came near its owner's property has experienced the essential continuity between animal territoriality and human property. Our domesticated cousins of the wolf are instinctively smarter about this than a good many human political theorists.
Claiming property (like marking territory) is a performative act, a way of declaring what boundaries will be defended. Community support of property claims is a way to minimize friction and maximize cooperative behavior. These things remain true even when the ``property claim'' is much more abstract than a fence or a dog's bark, even when it's just the statement of the project maintainer's name in a README file. It's still an abstraction of territoriality, and (like other forms of property) our instinct-founded models of property are territorial ones evolved to assist conflict resolution.
This ethological analysis at first seems very abstract and difficult to relate to actual hacker behavior. But it has some important consequences. One is in explaining the popularity of World Wide Web sites, and especially why open-source projects with websites seem so much more `real' and substantial than those without them.
Considered objectively, this seems hard to explain. Compared to the effort involved in originating and maintaining even a small program, a web page is easy, so it's hard to consider a web page evidence of substance or unusual effort.
Nor are the functional characteristics of the Web itself sufficient explanation. The communication functions of a web page can be as well or better served by a combination of an FTP site, a mailing list, and Usenet postings. In fact it's quite unusual for a project's routine communications to be done over the Web rather than via a mailing list or newsgroup. Why, then, the popularity of Web sites as project homes?
The metaphor implicit in the term `home page' provides an important clue. While founding an open-source project is a territorial claim in the noosphere (and customarily recognized as such) it is not a terribly compelling one on the psychological level. Software, after all, has no natural location and is instantly reduplicable. It's assimilable to our instinctive notions of `territory' and `property', but only after some effort.
A project home page concretizes an abstract homesteading in the space of possible programs by expressing it as `home' territory in the more spatially-organized realm of the World Wide Web. Descending from the noosphere to `cyberspace' doesn't get us all the way to the real world of fences and barking dogs yet, but it does hook the abstract property claim more securely to our instinctive wiring about territory. And this is why projects with web pages seem more `real'.
This ethological analysis also encourages us to look more closely at mechanisms for handling conflict in the open-source culture. It leads us to expect that, in addition to maximizing reputation incentives, ownership customs should also have a role in preventing and resolving conflicts.