With AppLovin buying MachineZone, is it on its way to amassing a Google-like empire in the mobile apps world? Also, we'll look at other walled garden acquisitions, like Twitter buying CrossInstall and Facebook buying GIPHY. Speaking of the book of faces, we'll tell you how its new ecom endeavor is different from what it's tried in the past, and we'll discuss what Walmart's and Target's earnings portend about the future of retail.