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This topic has come up a number of times in the past. Grant Ingersoll has corresponded with the lead of TREC, Ellen Voorhees, and with the Univ. of Glasgow (keepers of some of the TREC documents, see http://ir.dcs.gla.ac.uk/test_collections/
) about either obtaining TREC resources (even if the ASF has to pay) or creating a truly open collection. See http://www.lucidimagination.com/search/document/656d5ca50c8c9242/trec_collection_nist_and_lucene, specifically http://www.lucidimagination.com/search/document/656d5ca50c8c9242/trec_collection_nist_and_lucene#84e9e24ee9ff4779. On the Glasgow side, all conversations there were private, and thus not available. The gist of them is that the only possibility for distribution is to a limited number of committers within the ASF on a project by project basis (even though the ASF is purchasing) and that the burden is on us to maintain a list of people who have access to the documents. Ultimately, while the ASF was still willing to make the purchase, Grant felt it was too much of a burden and not beneficial to Open Source and has thus not proceeded with obtaining the collection.