“The Pepsi Like machine” in addition to being buzzworthy makes really good business sense. Lets look at this from a math perspective.
According to 2 different sources ( link 1 Link 2 ) the cost of a “fan” is over a dollar. One says 1-7 dollars, another says way over 100, but lets skip over all the different methodologies and say its over a buck – this way we get to agree on the main insight rather then the details of why the research is wrong. So, what is the cost of a soda ? Maybe 75 cents, or 1.25 ? The beauty of the coke like machine is that people are opting into a loyalty program for a free sample. The cost of giving away that soda is equal or less then the amount of dollars they would have spent to gain that fan. Additionally, the documentation of this stunt by pepsi translated into earned media dollars ( via viral video and blog editorials ) which is bound to give pepsi an edge in awareness and brand equity – that is… free advertising.
This was a great execution of digital marketing moving its way into physical computing that makes sense. They are also very lucky that they are some of the first ( not the first ) to ask people to trade their social capital for real assets. Because if everyone starts to ask fans to like their product for a free, people will start to value their privacy more then the transaction that occurs. A reverse tipping point comes into play between free stuff and privacy.
The other interesting thing here to note is that documentation has make this appear to be a huge campaign when this really just occured at once concert. Lets say it only had a reach of 100 ( I have no data to back this up). The video of this campaign itself far exceeded the actual number of people that got free product. This is where many guerilla marketing campaigns have gone where they set up a special campaign to reach only a few ( 007 promotion comes to mind (coke )) and most of the effort is spent on sharing this story throughout social networks in place of paid media. It really shows an interesting trend in how marketing dollars are moving from paid medias to earned and owned networks.