All Ellen Pao is doing here is guaranteeing overpayment for mediocre workers. Think about it. To get the best talent she'll have to pay top dollar. But that doesn't guarantee everyone hired is top talent.
If you read the summary carefully, they are not stating a salary value for a job in advance of making a offer to someone.
They are interviewing and then making an offer they feel is appropriate for that interviewee, that means that they can still adjust the offer based on the person in front of them (and who is to say the hiring managers don't offer less to women?). All thats changed is that the offer is set in stone, the interviewee either takes it or leaves it.
This scheme will live or die on how well they predict the job market for the roles they are hiring for but I don't see how it really addresses the stated goal of equalizing pay ranges between genders.