- a transaction recorder, and
- a global land records registry that [is] free of jurisdiction
I have no opinion on Propy itself except to say that it's early days and that a lot of these startups will come up with some very good ideas and then fail to execute those ideas in a sustainably profitable way and disappear, leaving only the very good ideas as evidence that they existed.
A "jurisdiction-free" -- that is, non-state-dependent -- global land records registry is one of those very good ideas provided that it can gain widespread adoption and that it has a sound underlying model for confirming the veracity of claims to property in land.
Assuming survival of technological society, in the future we might have hard, unmodifiable evidence of prior ownership of, and the nature of transfers of, particular parcels, removing one dimension of historical argumentation in conflicts like those between displaced Palestinian Arabs who once lived on, and the Israelis now living on, particular parcels.
Not that it would necessarily bring such conflicts to an end, but it would reduce the ability to game their history.
Of course, there still remains the root issue of how one would establish a rightful initial claim to ownership in land. The Georgists say it can't be done, and the Lockean formula is vague as to just how much, and what kind of, labor has to be mixed with land to establish ownership. But establishing legitimate title and recording title and transfer under some accepted scheme of legitimacy are separate problems. A blockchain does indeed sound like a nice solution to the latter.