Some recent observations on carrier (electronic and ionic) transport in thin film and nanostructured metal oxides and superlattices, where interfaces play a dominant role in overall conductivity response, are reviewed. Conduction in nominally pure oxides is compared to heavily aliovalently doped oxides (that correspond to changes in the Debye length over few orders of magnitude). The role of dopant segregation and their spatial variation in affecting transport is pointed out. The ability to utilize interfaces in enabling ultrafast-ion conduction as well as the creation of novel interfacial materials and implications in energy technologies as well as some scientific questions that may warrant further attention are highlighted.