Hi Stephen - based on the research I've done on this topic this example fits well the definition of gamification: using game-based design principles in non-game contexts.
The question is what constitutes 'game-based design principles', and that is a fair question. As for the non-game context, I think it's pretty clear, as you point out, that the Pepsico example is not a non-game context.
In Kevin Wehrbach's Coursera course on gamification he discusses the game-based design principles that can be leveraged when looking at gamification in the workplace.
The traditional game elements that first come to mind for many people are points, a leaderboard, status levels, and badges (PBLS). While these are certainly legitimate, and have been the focus of business use of gamification for the companies catering to the social media crowd (eg, Bunchball, Badgeville, others), there are game design elements beyond these, that can be leveraged as well, that don't require a social media platform to use them on (necessarily).
Some of these include a defined game space, rules, and willing acceptance of both by the participants. In other words, the participants have to be voluntary, not conscripted. Thinking about gamification using these elements requires a good deal of abstraction away from the PBLS that first come to mind when the word 'gamification' is uttered. Which is unfortunate, because it is already resulting in a lot of wrong-headed efforts that are bound to fail (Gartner reckons 70% or more of the gamification efforts companies have embarked on will fail, in fact).
So, with that in mind, the other key ingredient, beyond identifying the game space and rules, is coming up with an actual 'game' that would be interesting enough to the 'players' (ie employees), such that they would become willing participants in it.
As we know, sustainable behavior change is generally not easy to affect in the workplace at scale, so the obvious place to look is where there is already a behavior type occuring, that is seen to be beneficial by the business, which could be extended through the use of gamification.
In this case, Pepsi saw that employees were already interested in blogging about their brand out of a sense of pride. The brilliance of this case example is that rather than try to control it, and tamp down the enthusiasm that was clearly evident here, they decided to harness it, by creating a game space, rules, and rewards for 'winning.' The game space was blogging for public consumption; the rules were, the blogs would be subject to a review, and the ones that were deemed appropriate for external publication would be published; and the reward for winning was being able to point your friends, family members and colleagues to your blog post out on the public web.
This is simple, elegant, and subtle- but it does fit the definition of gamification. For my money, efforts like this are much more sustainable over the long term, and can generate powerful results for enterprises.
So - is this really anything dramatically new? Well, maybe not. It's more of a new way of thinking about things that we've been doing all along, that results in a reframing of how we view those things. The result is we become more focused on identifying other opportunities that fit that new frame, and thus become more deliberate about how we identify and evaluate them, and do something about them. Remind you of anything else this group has talked about?? :-) Knowledge management, anyone?