Coca-Cola has hit the ground running with a digital marketing blitz to increase fan participation in its World Cup-themed The Longest Celebration video contest and raise awareness that it’s one of the games’ deep-pocketed sponsors. Last week it turned to the newest social media marketing tool available, paying for Twitter’s “trending” tweets real estate, to gain extra buzz, making Coca-Cola the second company ever to pay for big tweets. And pay big time it did, spending in the five-figure range for 140 characters of promotion. But did Coke’s promoted tweet live up to its goal?

Coke is already by far the most successful World Cup sponsor in terms of augmenting its brand’s social media following, as seen from our latest weekly World Cup sponsor social media audit. During the first week of the World Cup it attracted nearly 170,000 new social media followers, far and away the most of any WC sponsors. But the pick-up is not evenly spread out. In that first week it attracted 2,300 new subscribers to its YouTube page, which is hosting the World Cup celebration video contest, and, during the same period, its Facebook page gained over 150,000 fans.

Last Wednesday, a big day for England and American soccer fans, the soft drinks marketer went the extra mile and used the relatively untested tactic of a buying a trending Twitter topic; prior to Coke, it had only been tried once before for Disney-Pixar’s “Toy Story 3.” Needless to say, because you and everyone you know has probably seen the movie, the first promoted tweet ever was considered a big success.

The second paid-for Tweet is also generating plenty of talk. Mashable praised Coca-Cola and its promoted tweet, citing the 86 million impressions on Twitter. One of the best parts, they note, is that “the expense was small relative to other ad buys,” as its cost only hit in the tens of thousands of dollars. Indeed, compared to World Cup prime time commercial slots this was chump change.

But just how effective was the promoted tweet in terms of building and maintaining an online brand following? It did a good job for its Twitter page, as it gained about 4,000 new eager followers since last Wednesday. But the promoted tweet was directly aimed to get Coke lovers onto the YouTube page, where it’s clear the numbers don’t match the hype. As we reported last week, Coke gained about 3,000 new YouTube subscribers in just one week after the start of the games. Since the promoted tweet, Coke’s YouTube page only gained about 800 new subscribers, which isn’t a small number on top of its already 10,000 strong viewers. But budgeting tens of thousands of dollars for a single social media ad buy seems like a dud when the company did just as well signing up new fans without without splashing out for a paid Tweet.

Of course, figuring out how many more bottles of Coke were consumed on account of the tweet is harder to do (particularly if the Tweet doesn’t direct the public to a track-able give-away or purchase possibility).

One thing seems clear, promoted tweets may be good for boosting a Twitter following. But the verdict is out on whether the promoted tweet is beneficial for the rest of the brand’s social media marketing efforts.