We weren't signed up but as a measure of the scale of this we still wound up with a couple of Imagination Library books through book exchanges or buying used online -- i.e. there are enough of these 300M books floating around that if you have a kid there's a good chance you run into them.

I like the sibling comment "We should be more ambitious with the people we build." -- there are so many great things people with some means can be doing!