I knew I should wait to post about this. There are now over 350 comments on Soni Sangha's NYT story of the stresses of operating an underground co-op nursery school in Brooklyn, so I'm pretty sure that everything that can be said on the topic has been.
I'll also assume/hope that at least one commenter mentions dads, because the article itself does not.
Underground Pre-K Groups, Often Illegal, Abound [nyt]
Previously, related, and similarly hotly commented upon: The Playgroup, Ann & Gordon Getty's invite-only, unlicensed preschool in their house