<http://schema.org/topics>
"apps,Aviary,news,contributor,features,Gadgets,hipstamatic,instagram,iPhone,iPhotography,Lists,Mobile,mobile apps,mobile devices,Photography,photo apps,Tech"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2011/06/02/mobile-photo-app-trends/>