Recent signs that the 3-year-old micro-blogging tool is making a mark in HR include:

• The Internet buzz that was created when a person landed a job at Cisco, said on Twitter that she’d hate the work and was called out on her remarks by another Twitterer.

• The fact that the Society for Human Resource Management used Twitter to announce that Jack Welch would speak at its annual conference in New Orleans in late June.

• The way discussions have broken out about using Twitter as a tool for both training and benefits communication.

But businesspeople are flocking to Twitter without much thought about its true benefits and risks, says Alison Davis, head of employee communications consultancy Davis & Co.

“The problem with Twitter is, it’s so cool,” Davis says. “People in organizations are jumping on the bandwagon without knowing what the bandwagon is.”

Twitter allows people to post messages of no more than 140 characters to the Internet, and individuals sign up to follow one another’s postings. But the free service also can act as a viral communication tool as individuals repost, or “re-tweet,” messages they receive to their networks of followers.

Unique visitors to Twitter soared from 475,000 in February 2008 to 7 million in February 2009, according to research firm Nielsen Online. What’s more, Nielsen found that Twitter is most popular among working adults.

Organizations are starting to tap Twitter as a marketing and customer service tool. Among them is SHRM. On March 19, SHRM chief operating officer China Miner Gorman broke the news via Twitter that Welch, the legendary former CEO at General Electric, would speak at the group’s annual conference. “Great news!” the tweet reads. “Jack Welch is kicking off SHRM’s annual conference in New Orleans in June. He’s a huge HR fan!”

Welch is replacing newsman Tom Brokaw as the keynote speaker on SHRM’s opening day June 28.

Twitter also has a role in employee training, says corporate learning consultant Jeanne Meister. She recently pointed to several possible uses of Twitter on her blog, including “reminders of upcoming training events and reminders of key learning content,” “pre-emptive help for learning a new process or procedure” and “links to new articles of interest.”

Twitter also can help with benefits communications, says consultant Jennifer Benz. The format’s forced brevity is a plus, Benz wrote in a recent blog item: “That means you have to get to the point fast and entice your audience to link for more information.”

But there are possible drawbacks to Twitter, Benz says, including the temptation to use confusing acronyms and the potential for Twitter-monitoring to suck up a lot of time.

Another danger with Twitter is the way loose tweets can torpedo firms or individuals.

Apart from the Cisco hiring case, another Twitter scandal involved a PR person whose disparaging comment about Memphis, Tennessee, angered Memphis-based client FedEx.

People are still struggling with the “publicness” of online social networks, Davis says.

Davis’ firm is experimenting with a Twitter-like tool called Yammer, which is designed to allow for private company networks.

Still, Davis suggests HR professionals visit Twitter. “You need to see for yourself what it’s about.”