The statistic, based on a survey of 700 Twitter users, suggests the service's value as a business-to-business marketing platform, alongside its emerging utility for consumer marketing.

"Twitter is a goldmine," Rumford said, adding that a number of big consumer brands are already on the site--including Starbucks, which currently boasts about 6 million followers.

Rumford also noted that small businesses are using Twitter to advertise, citing the example of a gourmet Korean taco truck business in Los Angeles which since its launch in November has built a following through Twitter: "The driver tweets where the truck will be 20 minutes ahead of time, and literally hundreds of people show up," one conference attendee confirmed.

Marketers can use Twitter actively or passively, Rumford says--in the first case by reaching out with promotional messages, and in the second by setting up a "listening engine" that allows them to track consumer sentiment in public postings on the site. Any active marketing must be handled carefully to avoid alienating consumers with the appearance of dishonesty or inauthentic, impersonal messages: "It's not a campaign, it's a conversation," he said.

As with blogs, Rumford conceded that "people are going to be saying bad stuff about your brand, and that's okay" because it can be an opportunity for customer service interventions. "I love it when someone says something bad, because then it's a chance to show your true colors," he said.

Companies are still mishandling this kind of functionality, however: Rumford cited the example of Motrin, which reacted slowly to widespread criticism on Twitter of an ad about pregnant women that was perceived as misogynist. Rumford added that efforts to drive people to particular online destinations can be tracked and measured by Google Analytics; Google also crawls and indexes all the conversation streams on the site.

Justin Goldsborough, social media manager for Sprint, said the company uses Twitter to track consumer sentiment as well as for customer service. But Sprint also uses Twitter and a corporate blog to coordinate business-related activities, according to Goldsborough, who noted the site's growing penetration of all areas of U.S. business. "Retail employees are on Twitter," prompting some concern among management, but Goldsborough pointed out that it can connect these workers more closely to both their customers and their bosses. He also pointed to the example of BestBuy, which has a communal blog and chat site used by thousands of employees. On the negative side, Microsoft's plan to get laid-off employees to give back some of their severance pay was rapidly derailed by criticism on Twitter.

Meanwhile, politicians are also on Twitter. According to conference organizer Beverly Macy, the Republican Party is using the site to hold discussions about re-branding the party.

Online social media can be a highly effective advertising medium, but there are some pitfalls that can seriously damage a brand, the speakers warned conference attendees. The central theme touched on by all the presenters was the importance of honesty and transparency in Web marketing that relies on word-of-mouth.

David Reis, the founder and CEO of DEI, an online word-of-mouth marketing company, recalled the condemnation heaped on Belkin, an electronics manufacturer, for paying users $0.65 per post to write favorable reviews of its products on Amazon.com. "Basically, it's a simple problem: They lied," Reis said, emphasizing that marketers should always be forthright about their identities and mission.

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