Recursive FOIA requests. Very neat :) Breadth first or depth first is going to be their main problem. The plus for the government is that if they lose a document they now have an off-site backup. Presumably the CIA is not playing ball because they have their own backups.
In Canada, similar requests had partially liberated the information contained in the Coordination of Access to Information Requests System that the Federal Government used to centrally manage ATI requests (our FOIA), so that people could do this kind of recursive research. The Conservatives disbanded the database in 2008 in order to remove this resource from being the target of ATI requests, and make it harder to get information to the public.
What a fantastic project.