The world discovered the power of Twitter during the past week, when Iranians provided a real-time account of their country's political unrest.

Minnesotans had a preview last fall, when political protesters and journalists used Twitter to chronicle events at the Republican National Convention in St. Paul.

Based on these undeniably compelling examples, it's tempting to anoint Twitter as the next great development in communications — and, in fact, many have done so.

Our agency has used Twitter with good results for several clients. Intelligently applied, it can be a great way for marketers to get the word out about a product or an event.

But before you jump blindly on the Twitter bandwagon, let me offer a cautionary note in the form of a recent study by faculty and students at Harvard Business School.

Researchers sampled the usage patterns of more than 300,000 Twitter subscribers. What they found:

• Half of all Twitter users "tweeted" less than once every two months.

• The top 10 percent most prolific users accounted for more than 90 percent of the tweets.

• The median number of lifetime tweets per user is one — meaning half of all the people with a Twitter account never post a single tweet.

On most social networks, the researchers note, the top 10 percent of users are responsible for about 30 percent of the content.

What this means is that, at least for now, Twitter has collected a relatively small population of rabid users who tweet relentlessly. Meanwhile, the masses sign up for an account out of curiosity and rarely use it.

As the Harvard study notes, "Twitter resembles more of a one-way, one-to-many publishing service than a two-way, peer-to-peer communication network."

In other words, Twitter isn't a way to keep in touch with your friends, like Facebook. It's more like a constant, flashing billboard carrying information from people with a definite message to get out.

For marketers, the implication is clear. If you can tap into a network of committed Twitter users, word about your product can spread quickly. Twitter super-users are engaged, in touch and love telling the world about their discoveries. It's like in the days of old media, when a mention by a prominent newspaper columnist could dramatically boost your company's profile.

But it's not automatic. Your message must have meaning to its intended audience, and you've got to be engaged in the Twitterverse. If you're one of those who tweets every two months, your odds of becoming the next Twitter sensation are minimal.