I'm 19 and I got my first cell phone last year. I never expected to text much, and in the beginning I didn't. However over time I've been using it more and more to the point where I have entire conversations via texting. The simplicity is ridiculous. It's like instant messaging, but anywhere. In addition far more people have a phone capable of SMS than they have an MSN/AIM (or equivalent) account.
As per the article, 13-17 year olds are using more than twice as many texts per month (~3300/mo) as 18-24 year olds (~1600/mo). After seeing the recent surge in email-based startups, where are all the startups focusing on SMS?