The New York Times has the story (here) of how residents who go through the trouble of clearing snow from parking spaces claim a labor-based, temporary "right" to those spaces, which they mark with orange cones, potted plants, lawn furniture, or just about anything else imaginable. The purpose of the scare quotes in the last sentence is to indicate that the term "right" is being used in a very loose sense; it is not at all clear what party, if any, has an enforceable "duty" not to take the parking space. The "rights" at issue are really in the nature of extra-legal claims based on presumed social norms (or even, dare I say it, natural law).
Are such claims enforceable? Well, according to the New York Times story, in South Boston such claims are legally authorized for up to 48 hours after a snow storm. But it's not clear how strictly that limitation is enforced. In any case, it's doubtful that the claimed right to a parking space could be enforced in a court of law. But such rights often are self-enforced by the claimants, e.g., with threats of slashed tires, broken mirrors, or other acts of retribution, which themselves may be technically illegal, if difficult to enforce. One problem of self-enforcement, of course, is the heightened risk of conflict escalation including the potential for violence.
I don't know of any empirical studies that have investigated the prevalence of temporary private property claims in public parking spaces after snowstorms. Certainly, they have become a normal feature in various neighborhoods in many cities subject to significant snowstorms. It would be interesting to learn just how prevalent the norms are, how they are similar or differ in structure and enforceability from one city (or neighborhood) to another, and what legal acceptance, if any, they have attained in various jurisdictions.