Blogger Stevel Rubel spoke with Big Think yesterday on the the future of internet advertising, the semantic web and digital media. He's a smart guy. He also has a really cool title at his day job.

As Director of Insights at Edelman Digital, Rubel follows internet trends and flags them for their significance to the world of PR. He's been at it for over a decade and has been responsible for introducing social media to companies around the world.

On Twitter, Rubel noted that unlike many previous memes in social media (like Second Life), the microblogging service just keeps on chugging with traffic growing from 3.4 million last October to 19.4 million this month. It's sub-domain, Twitter Search, has grown 400% in the past six month alone.

The trend is for these kinds of sites to flare up and fade away, Rubel said. But Twitter seems to be bucking that trend at the moment.

Part of Twitter's genius is that it is used increasingly as a platform for marketers to get the word out about their products, something to which previous iterations of social media were not hip.

"The reason it has taken off for marketers is that, one, the community is there. Two, it's lightweight," Rubel said. "The more savvy brands are using it as a customer service tool and a feedback mechanism."

The full interview with Rubel will be released shortly.