How private is the private beta?

Question

With "Mathematics Educators" being ready for the beta phase, do I understand it correctly, that the next step is going to be a private beta?

How closed and private is it going to be? Are only users commited to this proposal eligible for it? What's the policy?

Answer 1

As of December, 2013, private betas are not really private. It's probably better to think of it more like a limited beta. The bar to entry was always fairly low since the invitation included a link to the private beta that could be shared everywhere.