It sounded like they're still a little squishy on the details--I asked about money and they said:
"Some sort of equity contract would be drawn up on a case-by-case basis based on how many purchases are made. We will make this process transparent by offering up the purchase reports directly from Apple. Suffice it to say that we'd certainly not take as much as the typical publisher takes.If you're interested, check out the product here.
Also, this might be a really good opportunity for additional revenue if new illustrators and authors do not have existing contracts with publishers for their stories."