Boyd found that the percentage of Twitter users who retweet is fairly small, but she expects that number to increase once the retweet button is incorporated. In her research, Boyd found that 11 percent of the retweets examined contained commentary. But she says that number likely underestimates the phenomenon, as she only looked for comments at the beginning of the message.

"Retweeting is primarily used by the geeks and news folks," she says. "What's really starting to hit [Twitter] in large numbers... are those involved with the pop culture." Boyd expects that a retweet button will bring the practice to those millions of users who follow celebrities, such as Twitter fanatics Ashton Kutcher and Oprah Winfrey, for example. "We're going to see information spread from populations who haven't engaged in that way [before]. We'll see an evolution of the behavior," says Boyd. "It will become a way to validate or agree with other users' content."

Users often employ retweets to provide context in conversation, says Susan Herring, a professor of information science and linguistics at Indiana University and editor in chief of the Language@Internet journal. "I can't imagine that [the new Twitter tool] will be very satisfactory to Twitter retweeters," says Herring. "A retweet plus a comment is a conversation. A retweet alone could be an endorsement, but it's a stretch to view an exchange of endorsements as a conversation." Herring does agree that it will increase retweeting and broaden the range of users who retweet.

Retweets are not just of interest to users but also are valuable to companies and researchers who strive to keep track of how ideas spread. Retweeting "is this elegant viral mechanism," says Dan Zarrella, a Web developer who studies viral marketing in social media. "The scale and data you can extract from [retweets] has never been possible with [other] viral or word-of-mouth communications," says Zarrella, who claims to have a database of more than 30 million retweets.

"I think that having a button and supported structure of retweeting is definitely a good idea, but I disagree with the implementation," Zarrella says, and suggests using a format like third-party Twitter tool TweetDeck and others do: pressing a retweet button there will automatically copy and paste the old link with the "RT" syntax, but the tool still allows the retweeter to modify the text.

By taking out the "RT @username," Twitter is making it impossible for users to search for retweets themselves, says Zarrella. "They're limiting how much you can analyze retweets." Zarrella speculates as to whether the retweet button might have been created so that, down the road, Twitter can charge for different features, such as extensive tracking of retweets.

In addition to showing the original tweeter's image, the new Twitter button will also show the latest 20 retweets of a post. "If they show the breadcrumbs of the trail of everyone who retweeted, that's a good thing," says Steve Garfield, a new media advisor to several large companies and prolific video blogger. "I like to add value to my retweets by adding a comment, to tell people why I like it." If the new function doesn't allow for comments, Garfield says users will just design a new way or revert to the old way.

"People will continue to repurpose Twitter to meet their needs," predicts Herring. "I can't imagine that those who are passionate retweeters will discontinue their practices."