Minireview: http://www.appysmarts.com/application/there-s-no-place-like-space-all-about-our-solar-system,id_27441,path_0.php
Interactive book: There's No Place Like Space!: All About Our Solar System by Oceanhouse Media [ages: 4-6, iPad, iPhone]
An interactive book from the Cat in The Hat's Learning Library about the Solar System.

Every day: newest apps for kids, toddlers, preschoolers, discounts and free offers: http://www.appysmarts.com