Although it is not the first such stamp to be released by a national postal organization, it is the first is available to private companies to use for promotion.
Macanudos is a mobile marketing company out of Granada, Spain. They are working with the Spanish post office to extend a postal campaign begun in 2007. That campaign allows private companies to promote their brands in conjunction with the country's stamps. First out of the gate is a QR proof-of-concept, said the company's press release.
"The Spanish postal stamp consists of a QR code that, when scanned with a mobile phone and with right software will redirect the phones browser to an Internet address in which the user will be able to view a video, in this case, about the Alhambra of Granada."
"Tu Sello," or "Your Stamp" is the program that allows private companies, as well as independent governmental and non-profit organizations, to take advantage of the ubiquity of stamps to promote themselves, thereby shoring up the post office's bottom line as well. You may be able to scan future letters in and from Spain to get deals on ski equipment or information on wines from local vintners.