Product Integration?

Recently in class, we discussed the differences between product placement and product integration. It seems that product integration as taken over as most prominent choice for making sure that viewers witness their products, even if they choose to skip over the commercials. Product integration is a less obvious form of advertising, and it seems to do a better job of fitting with the direction of the story. Hence the title "integration". What I am having trouble wrapping my head around is what if the product or the brand is an integral part of the story?

This question was spawned from watching the movie "Zombieland". Within this movie there were several examples of product integration in this movie. A few examples are when the main character, Columbus, is playing World of Warcraft and drinking Mountain Dew. This showcases how he spends his time, and it creates his character's persona. However, those are not the examples that put this question in my head. One of the other main characters in this movie, Tallahassee, has major obsession with finding a twinkie in this post apocalyptic land. Now this obsession is not just limited to one scene, and it is certainly more than just a minor blip in Tallahassee's character. His hunt for this twinkie puts the characters in several amusing situations. This is the first of those situations.

http://www.youtube.com/watch?v=7BdXZPcE3eA

With all the product integration we see today, it seems like the screen writers are also becoming script writers for advertisements. However, I think this twinkie obsession is more creative based than it is advertising. For one thing, Hostess snack cakes are not currently a frequently advertised product. So unless the movie corporations decided to write in this elaborate plug for Hostess products, then I am going to have to say that this was put in by the original writers. If the purpose of this product plug was to be creative, and not to advertise, then I do not think we can call it product placement or integration. I would suspect that the writers of this movie would not want their creativity to be misconstrued as selling out.