I'm the CTO of an organization that has been delivering cheap tablets with educational content to rural areas for several years: http://www.rumie.org/

Some of the challenges: 1) Making sure the tablets actually make it to the people that need them and aren't repurposed/resold 2) Lack of internet so all content and apps need to be offline-friendly 3) Loading the tablets with content appropriate to the region (language, cultural)