Do you know of any designs that require a quorum at each level prior to trust? BitCoin seems to be having success with this model, but I'm wondering if anyone's built something like that with the primary intent of creating a directory service.
That said, your idea about poaching the Bitcoin quorum ideas is a good one. Essentially a data structure, equivalent to the block chain, where it only gets authenticated if enough people ack that its the most valid version of reality. Probably a publishable paper in exploring that question.
You may see an email from me in the next few weeks asking for feedback on such a paper.