In the current mad frenzy rush to all-things-Twitter, one data point seems to be missing from the 140-character discussion: Who is Twittering? And, similarly, who is out there ‘listening’ to your Tweets?

The Twittersphere is exploding.

According to an analysis of February data by comScore blogger Sarah Radwanick, over the past several months, comScore has been watching how quickly traffic to Twitter has exploded:

• Worldwide visitors to Twitter approached 10 million in February, up an impressive 700+% vs. year ago.
• The past two months alone have seen worldwide visitors climb more than 5 million visitors.
• U.S. traffic growth has been just as dramatic, with Twitter reaching 4 million visitors in February, up more than 1,000% from a year ago.

But what are the demographics of Twitter users?

Well, marketing friends, it seems that we are in for a surprise.

Twitter Followers are older than you think

According to Reuters blogger Alexei Oreskovic, while Twitter “has the fast-growing microblogging service has all the earmarks of a young person’s pastime” Twitter devotees are grayer than you might expect:

The majority of Twitter’s roughly 10 million unique Web site visitors worldwide in February were 35 years old or older.

What Oreskovic discovered was that 18-24 year olds, the traditional social media early adopters, are actually 12 percent less likely than average to visit Twitter. It is the 25-54 year old crowd that is actually driving this trend. More specifically, 45-54 year olds are 36 percent more likely than average to visit Twitter, making them the highest indexing age group, followed by 25-34 year olds, who are 30 percent more likely.

Twitter is a rare example of older people embracing a new Web technology at such an early stage, says Andrew Lipsman, director of industry analysis at comScore

According to comScore, again, the skew towards older visitors, although perhaps initially surprising for a social media site, actually makes more sense than one might think at first.

With so many businesses using Twitter, they argue, along with the first generations of Internet users “growing up” and comfortable with technology, this is a sign that the traditional early adopter model might need to be revisited. Not only teenagers and college students can be counted among the “technologically inclined,” which means that trends are much more prone to take off in older age segments than they used to. And with those age 25 and older representing a much bigger segment of the population than the under 25 crowd, it might help explain why Twitter has expanded its reach so broadly so quickly over the past few months.

All this is actually great news –but only if your target audience is in the 25-54 year old crowd. But if it isn’t, you may be wasting your time (even if you are having fun).

We at WiderFunnel for example can attest to the (admittedly) surprisingly positive impact Twitter is having on our web traffic as well as new client generation.

We now have several examples of new clients finding us not by searching on Google (the most common method) but by searching for Conversion Optimization on Twitter. Since the decision-makers we target are at the C-suite level (a group normally populated by older segments) it all makes sense.