Last week I reported that Facebook had begun testing a new form of sponsored event ads. Today the first branded Facebook event appeared on the site homepage. This event was for Starbucks’ election day free coffee offering. The event has so far attracted close to 38,000 users and it continues to grow.

As I wrote when this new form of advertisement was first spotted, this is a substantial revenue opportunity for Facebook. Why? Well Facebook events are one of the most viral components of their site. I took a look through my newsfeed and ironically, the Starbucks event had already hit enough of my friends to show up in my newsfeed (as pictured below).

This wasn’t sponsored distribution, it was simply free distribution because the event had attracted so many of my friends to the event. It also appears that events rank highly in Facbeook’s news feed algorithm. Once a few of your friends attend the same event, you will regularly see a notification confirming their attendance.

The company clearly continues to test out new forms of advertising and honestly I think this form is one of the most powerful ones offered. Imagine the promotional budgets of large festivals and concerts and how this new form of advertising could practically transform the industry. While this is an early proof of concept, it’s exciting to see Facebook continuing to test new forms of advertising.