Nielsen just released its May 2009 data on social networking and blogging. Verdict? People still like that social media stuff.

Apparently, the average person spends 67% more time (year-to-year) utilizing social media mechanisms. Not surprisingly, Twitter.com was the fastest-growing Web brand in May 2009, increasing 1,448% since May 2008. Pretty impressive for the start-up, who has yet to figure out how to make money despite exploding popularity.

Even if you have been living in a cave, you've at least heard of Twitter by now. Most notably, the tweeting service that started off as a gossip forums for adolescents with iPhones has turned into a catalyst of political revolutions. Twitter has been identified with two mass protests in recent months — Moldova in April and Iran last week. As hundreds of thousands of people took to the streets to oppose the official results of the presidential election, Iranian officials were completely stumped when students began using Twitter to silently and efficiently organize.

Nielson also reported that Twitter had 1.2 million unique visitors in May 2008 to 18.2 million in 2009. However, despite being the fastest-growing brand year-over-year, Twitter’s month-over-month growth has begun to plateau, increasing mere single digits in April. (The average time per person on Twitter increased 175% year-over-year, however, month-over-month growth was flat, decreasing 1% from April 2009.) The slowing trajectory of Twitter may indicate that 2008 will be a hard year to repeat in terms of growth. There has been speculation that Twitter is doomed to hit a lower equilibrium of users as the service matures. Currently, more than 60% of Twitter users quite the service after less than a month. Looks like that super sucky statistic is starting to catch up.

Download Nielson's social media report here.