BetaNews continues its side-project of tracking of the E-pizza zeitgeist as Pizza Hut launches a Facebook app that allows users to order food through the social network.

Online media analysis firm comScore ranks Facebook as the most-trafficked social media site in the world, and the fourth most trafficked site altogether. Its application platform is an ideal place for companies to engage and intelligently target users, and has already been capitalized upon by the likes of Levi Strauss & Co., CBS, and Neutrogena.

Those companies will soon be joined by Pizza Hut.

The "Pizza Hut Interface" will integrate Facebook's main commerce system with pizzahut.com's registered user info, allowing users to browse menus and order food without leaving the Facebook window. This "Social Network as Portal" concept is extremely valuable to both the actual site and its partners, according to a recent study by Steve Rubel for Advertising Age. Rubel anticipates that contextual ads (like Facebook's social ads) will soon be triggered not only by keywords, but also by social algorithms.

And while Pizza Hut's Facebook application is a tool of sorts, it is just as much an interactive, socially-oriented, and above all, useful advertisement.

As BetaNews has discussed in the past, online pizza delivery is now a billion dollar industry that reflects the widespread acceptance of trends in advertisement, communication, and e-commerce. In other words, when the pizza guys start doing it, you know it's going to stick around.

Social networks have existed in earnest since the late '90s, and Classmates.com is generally credited for creating the first usable site strictly for the purpose of keeping in touch with a large number of individuals. The concept has taken off during this decade with the successive launches of Friendster, then MySpace, and now Facebook. Internet Market Statistics group eMarketer expects 44.3% of US Internet users will be active on at least one social networking site by the end of 2008.