Twitter’s business model has been officially confirmed by co-founder Biz Stone, which has said that Twitter is developing add-on tools and services for businesses and professional users of Twitter. These premium tools will be introduced by the end of 2009.

But Stone dismissed the notion of selling advertisements on the popular service at this time, even though ad revenue is the main way most Web start-ups manage to stay in business while keeping their service free for consumers.

“There are a few reasons why we’re not pursuing advertising — one is it’s just not quite as interesting to us,” Stone told the Reuters Global Technology Summit in New York via videolink from San Francisco.

Twitter is currently looking to crawl links included in tweets and index the content of these pages, which means that Twitter search will no longer just be a snapshot of a stream of tweets occuring in real-time.. but an archive of webpages that have been historically tweeted or mentioned by Twitter users.

This was mentioned by Santosh Jayaram, currently Twitter’s VP of Operations and formerly a the VP of search quality on Google. What’s interesting is that Twitter Search will develop a ‘reputation’ ranking system’:

As you should probably know by now, Ashton Kutcher beat CNN to reach 1 million Twitter followers. But he didn’t just do it with the web. Lamar, the third largest billboard company in the US donated 1,133 digital billboards advertising Kutcher’s Twitter profile. This amounts to 34 million impressions.

Some say it’s just a PR stunt to promote Twitter, CNN and even Oprah. I was never under the illusion that it was anything else but that. Come on, Kutcher is a celebrity. The whole deal about the race being an exercise in social media triumph over old media is not entirely accurate.

Comscore stats show that Twitter traffic has increased by 131% to reach 9.3 million US visitors. But what is more interesting is research which shows that Twitter users are 2 or 3 times more likely to visit top online news sites like Yahoo News, CNN and MSNBC than the average person.

For example, while 17 percent of the total U.S. Internet audience visited CNN.com in March, more than double that percentage (38 percent) of Twitter.com visitors did so. So these data firmly establish that there’s a strong relationship between Twitter users and news consumption.

The LA Times has a good two part interview with Jack Dorsey, one of the founding fathers of Twitter. There’s some choice bits here that’ll I’ll just highlight, go check the full article for more.

On choosing the name ‘Twitter‘:

We wanted to capture that feeling: the physical sensation that you’re buzzing your friend’s pocket. It’s like buzzing all over the world. So we did a bunch of name-storming, and we came up with the word “twitch,” because the phone kind of vibrates when it moves.

While Twitter was king when it comes to downtime among social networks in 2008, it has gradually improved. 84% of Twitter’s downtime happened during the first half of 2008 while its availability has improved significantly in the second half of 08. Pingdom has a PDF report on social network downtime and it answers some good questions about why availability is crucial to a social site’s growth, especially for a real-time service like Twitter.

Twitter news of the day. Better search integration to come. Biz at the official Twitter blog talks about testing a new interface which places search and trend features currently found on the Twitter Search page in the top corner of each profile. I’m just wondering… why only now? Many people have been clamoring for an easily accessible search bar on the same profile page and this would be a terrific addition. No more need for tools like Power Twitter anymore.

It will be interesting to see how else they plan to develop Twitter search beyond the basic change in interface usability.

While Twitter users span a large demographic, a good amount of them fall within a similar pattern: young adults. According to research from Pew Internet, the biggest Twitter user group are adults from 25 to 34 with many of them being mobile savvy.

Nearly one in five (19%) online adults ages 18 and 24 have ever used Twitter and its ilk, as have 20% of online adults 25 to 34. Use of these services drops off steadily after age 35 with 10% of 35 to 44 year olds and 5% of 45 to 54 year olds using Twitter. The decline is even more stark among older internet users; 4% of 55-64 year olds and 2% of those 65 and older use Twitter.

Maybe Twitter did pay attention to some of the ‘how-twitter-should-monetize’ ideas floating around the web. The co-founder of Twitter, Biz Stone talks to Marketing Magazine on Twitter’s possible business model:

Co-founder Biz Stone told Marketing: ‘We are noticing more companies using Twitter and individuals following them. We can identify ways to make this experience even more valuable and charge for commercial accounts.’ He would not be drawn on the level of charges. Stone said it could also create revenue-generating features to tap into the way brands use Twitter as a hybrid marketing and customer-service tool.

More irrefutable proof of Twitter’s continual growth and surge into the mainstream. Hitwise reports that last week Twitter became one of the 100 most visited websites in the UK for the first time.

It ranked 91st within All Categories, placing above online heavyweights such as Expedia UK (96), Gumtree (100), easyJet (101), Digital Spy (103) and Money Supermarket (105). Twitter traffic has already more than trebled this year, and much of that growth has come since we last wrote about the site in January… Over the last 12 months traffic to Twitter.com has increased 27 fold. However, the service is likely even more popular than our numbers imply, as we are only measuring traffic to the main Twitter website.