David Wojick has published "SCOAP3 Lifts Off: An Interview with Ann Okerson" in The Scholarly Kitchen.
Here's an excerpt:
Q: SCOAP3 seems pretty complicated to me. As I understand it they make deals with leading particle physics journals, so that when those libraries that participate in SCOAP3 pay the article publishing charges, everyone's subscription price is either lowered or eliminated, depending on whether some or all of the articles are paid for. Is that correct?
A: Roughly put, that's true. "They" are "we" in this case. Let me note here that without the interest and participation of the publishers, SCOAP3 would not have launched on January 1st, already with hundreds of 2014 articles in the SCOAP3 repository at CERN and now flowing in on a daily basis. The SCOAP3 Technical Working Group developed, in conjunction with the Steering Committee, a set of criteria that formed the basis for publisher participation. Publishers received the Invitation to Tender and responded by describing in detail the way in which they would participate and at what cost per article.