But online fame, negative or positive, is fleeting.

Social media consumer buzz about the controversy peaked on Tuesday--the day after J&J pulled its ad about the back pain experienced by mothers who carry their babies in slings--and has already pretty much petered out, according to Vitrue, Inc.'s Social Media Index.

SMI measures online conversations about major brands taking place through Twitter, social networking, blogs and video-sharing.

SMI's tracking shows that Motrin's share of all social media mentions of the five leading over-the-counter pain relievers started at 32% on Monday, hit a crescendo of 39% on Tuesday, dropped to 36% on Wednesday, and was down to 27% by Thursday.

The online shares of conversation for four of the competitive brands tracked during the same four-day period--Bayer, Advil, Tylenol and Aleve--seemed little affected by the Motrin controversy Monday through Wednesday. Their shares all hovered in the 19% to 21% range during those three days. Thursday, however, shares for all three jumped to between 22% and 25% ... just as Motrin's mentions were plummeting.

In other words, by Thursday, there was very little difference between the number of mentions of Motrin and its four key competitors. (Aleve was also tracked, but its share of online conversation was miniscule compared to the others. It started at 3.4% on Monday and ended at 3.8% on Thursday.)

SMI also showed that the lion's share of the Motrin buzz--about 95%, in fact--was generated through Twitter.

The new Word Pairing Report on SMI, which enables measuring to what degree a given adjective or attribute is being associated with a given brand, confirmed that Motrin had a very large social network "footprint" last week, and also yielded some intriguing results.

Vitrue ran the Motrin brand name against adjectives and keywords that were likely to apply to OTC pain relievers (inflammation, arthritis, pain relief, relief and inexpensive), as well as words that cropped up on the Web as part of the controversy (mommy blog, angry, controversy, backlash, protest, offensive and "babywearing," a term used in the ad that caused the stir). It also ran the brand against the brand's tagline, "We feel your pain."

Vitrue did the same with competitive brand Tylenol, and in addition to the terms above, included Tylenol's tagline, "Feel better" in the adjective/keyword mix.

At least during this past week, Motrin scored highest when paired with "inexpensive," indicating that the brand is being associated in online conversations with being an inexpensive alternative to other brands. (Tylenol's association with "inexpensive" was much lower.) This would seem a good thing for Motrin--particularly in the current economy, notes Reggie Bradford, CEO of Vitrue, a firm that helps global Fortune 500 brands engage with customers through social media.

On the other hand, Motrin's associations with the word "relief" and "pain relief" were considerably lower than Tylenol's, a not-so-positive indicator for the J&J brand, Bradford says.

Motrin's association with the words "mommy blog," "babywearing" and "offensive" were also very high. Associations between the brand and the words "angry," "controversy," "backlash" and "protest" were somewhat lower, however.

While the ad-related online buzz appears to be subsiding now, Motrin's work should just be beginning, points out Bradford.

"J&J did the right thing by apologizing and pulling the ad once it was clear that the ad's tone had hit a negative nerve among some mothers and set off a rapidly spreading firestorm," he says. "This episode obviously confirms the inescapable influence of social media on brands today, but it also points to opportunities.

"The fact that people care enough to tweet or blog about Motrin indicates that there's passion about the brand. Motrin should now be able to take the feedback, continue the conversation, and harness that passion for the positive.

"In addition, this example of social media's power seems to indicate that there may be opportunities to get some feedback through social networks that could inform creative direction," he says. "This is not to suggest that the creative process should in any way be turned over to consumers."

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