UMA Trust Model
Several documents produced by the UMA Work Group related to trust.
http://docs.kantarainitiative.org/uma/draft-uma-trust.html
Specification documenting the binding obligations on UMA participants. (You can see the old document that used to live on this page by visiting old revisions.)
Measuring Elements of Trust
Domenico Catalano's work on analyzing the UMA trust proposition.
More trust-related documents to come!
NOTE: The short link http://tinyurl.com/umatrust takes you to this page.