Damon Cortesi, the developer who helped create the infamous Twitter douche bag index at Startup Weekend, has landed a gig as an entrepreneur-in-residence at Madrona Venture Group. The move signals that the Seattle venture capital firm is getting serious about Twitter, the fast-growing microblogging site that limits users’ messages to 140 characters.

"We’ve kicked around a lot of ideas and we are trying to get up the learning curve as quickly as we can," said Madrona’s Paul Goodrich, adding that the firm is investigating whether a business can be built around the social networking phenomenon.

The 28-year-old joined Madrona about a week ago and is working on various ideas, with the developer helping the firm figure out ways to navigate the ins and outs of the rapidly changing service. 

Cortesi is a bit of a star in the Twitter universe, with more than 3,500 followers and Twitter apps under his belt such as TweetStats (measures the number of tweets per hour and per month); TweepSearch (searches followers’ bio information) and My First Follow (shows your first Twitter follower.)

And then there’s Tweetsum, which got huge laughs when it was introduced at Seattle Startup Weekend two months ago. Tweetsum operates the Douche Bag Index (DBI), a scoring system which determines whether someone is worth following on Twitter.

In fact, Goodrich said that Madrona discovered Cortesi through that 54-hour coding marathon. "We liked what he was doing, and he wasn’t just talking about it, he was doing it," Goodrich said.

Cortesi’s involvement with Madrona doesn’t necessarily mean that the firm will start a company around Twitter.

At this point, Goodrich said they are just in the exploratory phase. As early-stage investors, he said they are investing time, money and resources into figuring out how the ecosystem works and whether money can be made from it. (As part of that effort, Madrona and Perkins Coie are co-sponsoring two upcoming seminars about Twitter.)

Many have doubted whether money can be made through the short-form writing found on Twitter. And while Twitter’s quick rise into the collective consciouness has left many scratching their heads and casting jokes, others view it as an entirely new communication platform.

There are a few things that have attracted Goodrich’s interest. For one, numbers released this week by comScore show that it is the fastest growing social network with visitors doubling to 9.3 million during the month of March. That’s mind-numbing growth. But Goodrich also said that Twitter users tend to skew older, which opens up potentially interesting business ideas.

Building money-making applications around larger social networks isn’t easy, as Madrona discovered after backing Facebook application Bevy. The Seattle online fashion startup struggled to gain traction, annoucing earlier this year that it was seeking a buyer.

Cortesi didn’t comment for this story, though he obviously has a lot of ideas running through his head. In a Tweet this week, Cortesi wrote:

"So much cool stuff to work on today, I’m literally jumping up and down."

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