Whether you use QR codes or not, its undeniable that mobile tagging has become an integrated part of the marketing landscape. Popping up in print advertising and corporate-sponsored event/experiences, there still seems to be a lot of confusion about the application and usage of mobile tagging in delivering a more comprehensive marketing and retail message. PSFK just released a great "Future Of" report exploring some key trends in the field and interviews with experts an innovators in the field. Worth a look for those who work in development.