If you think gathering connections on LinkedIn is harmless, think again. Say you’re an executive whose connections consist mostly of clients. If a client or colleague recommends someone and you accept them into your network, you could unintentionally grant a competitor access to an unofficial client list, said Terry Gudaitis, vice president of cyber intelligence with the Arlington firm Cyveillance Inc.

Advertising and new media marketing executive David Saunders has a phrase to describe social media Web sites LinkedIn, Facebook and Twitter. He calls them “The Holy Trinity of Social Media.“ LinkedIn, the oldest, and Facebook are the father/son, said Saunders, president of Madison + Main Advertising & New Media. Twitter is the Holy Ghost, because “people are still mystified by it,“ he said.

A Seattle woman tweets from an airport that JetBlue’s birthday present to her was forgetting to put her wheelchair on her flight. Seven minutes later, an airline official tweets back that the crew will work quickly to make things right. On a Facebook page used by Delta Air Lines, a traveler suggests Delta wrap its Wi-Fi fee into its ticket price rather than charge separately. The airline doesn’t respond. The page mainly promotes the airline, talks up new services and offers travelers tips on popular things to do in the cities Delta flies to, such as Las Vegas.

As the two men campaigning for Virginia governor make last-minute sound bites to get out the vote on Tuesday, the virtual cocktail parties they host on their Facebook fan pages have exploded in activity. Both campaigns have rolled out Facebook pages, Twitter accounts, YouTube videos and other social media tools to reach voters over the course of the race, in addition to their primary Web sites.

Times sure have changed in the cross-promotions world. Years ago, when I taught the concept of cross promotions, it was simple: Noncompeting businesses promoted one another via usage of fliers or coupons, with the aim of sending customers back and forth. It was, and remains, one of the cheapest and most effective methods of increasing traffic for most small businesses.

David Ragan and his sponsor, UPS, keep fans posted through their Twitter feeds. Social media’s various incarnations—Twitter, Facebook and the like—serve different purposes, but the results are largely the same: They bring groups of people closer together through what often amounts to simple, informal conversation. NASCAR and many of its teams and drivers have wasted little time delving into this phenomenon.

Verizon FiOS customers: You can now tweet or update your Facebook status from the comfort of your couch even if you don’t have a laptop or smartphone. In addition to adding several high-definition channels to its lineup, Verizon FiOS now lets video and Internet customers take advantage of social-networking features. Using your remote control, you can post a Twitter tweet about a television show, read what others are tweeting and check out whose doing what on Facebook.

KABUL—Taliban threats scared voters and dampened turnout in the militant south yesterday as Afghans voted for president for the second time ever. Insurgents killed 26 Afghans in scattered attacks, but officials said militants failed to disrupt the vote. After 10 hours of voting, including a last-minute, one-hour extension, election workers began to count millions of ballots. Initial results weren’t expected for several days.

A hacker attack yesterday shut down the fast-growing messaging service Twitter for hours, while Facebook experienced intermittent access problems. Twitter said in its status blog yesterday morning that it was “defending against a denial-ofservice attack,“ in which hackers command scores of computers to access a single site at the same time, preventing legitimate traffic from getting through.

A hacker attack Thursday shut down the fast-growing messaging service Twitter for hours, while Facebook experienced intermittent access problems.

The British government has told civil servants: Go forth and tweet.

Judaism’s holiest prayer site has entered the Twitter age.

Call me Ishmael. 2:48 PM December 17th from web Have decided to go see watery part of world. Wish me luck! 4:09 PM December 17th from web Rooming for night at Spouter Inn. Nice place. Popular, too. Needs better lighting tho. 6:21 PM December 17th from web Dumplings for supper!

Iran clamped down on independent media in an attempt to control images of election protests, but pictures and videos leaked out anyway, showing how difficult it is to shut off the flow of information in the Internet age.

Ahead of the 20th anniversary of the bloody crackdown on Tiananmen Square this week, Chinese authorities have rounded up dissidents and shipped them out of town. Now, they even have shut down Twitter. Along with their usual methods of muzzling dissent, the authorities extended their efforts yesterday to silence social networking sites that might foster discussion of any commemoration of the events of June 3-4, 1989.