I should be able to restrict editing to the Person who created a Thing

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Security
Summary: This is coming up in several use cases: I have a "directory" Space where people can create Things, and only those creators (and the Editors) can then edit them.
This is what we want for the Rolls Ethereal, for example, as well as some of the LARP use cases that have been described. It would also be appropriate for, say, a Community Job Board use case. (Which I'm thinking about for a possible Scala Boston community.)