Last week, a similar episode occurred in my real life, when I prepared to leave a meeting with someone I had never met before but really liked. This time, my host asked me if I was part of LinkedIn, a buzzy Web site intended to link people with similar business interests.

In the case of LinkedIn, I was privately relieved to be able to say that I had not yet joined, although I noticed that people kept asking me if I was a member. And, I must acknowledge that the invitation, like the one in Second Life, irked me on some level.

Don’t get me wrong. I like people, and interacting with so many of them is one of the great pleasures of my job. And, heck, all that journalists do all day long is call people who may not want to hear from them. But I wouldn’t want to join any social networking Web site that would want me as a member.

I say this in full recognition of the rampaging popularity of social networks and the fact that big media companies — particularly the large club that still envies Murdoch’s snatching of MySpace in 2005 for what now looks like a knockdown price — have developed a full-bore teenage crush on these businesses.

Social networking is a close cousin of the other obsession of the moment: user-generated content. Of course, there is a difference. User-generated content is basically anything someone puts on the Web that is not created for overtly commercial purposes; it is often in response to something professionally created, or is derivative of it. So, it could be a blog, a message board, a homemade video on YouTube, or a customer’s book review on Amazon.com .

Social networking, on the other hand, is something potentially deeper — it represents a way to live one’s life online. In many ways, it is the two-dimensional version of what sites like Second Life aspire to be in 3-D: the digital you. And that ties to another earnestly overused term of art at the moment: engagement.

Engagement basically refers to the amount of time people spend doing one thing — reading a magazine, watching a TV show — but also to the depth of their participation.

Sony, for instance, paid $65 million for a video-sharing site called Grouper.com and started a nifty service through which you can load your favorite clip from one of its movies — say, Jack Nicholson barking, “You can’t handle the truth” at Tom Cruise in “A Few Good Men” — onto your MySpace or Facebook page.

Over the last few weeks, other media companies have accelerated their efforts in social networking. For example, the Hearst Corporation on January 8 bought a small company called eCrush.com. Many of the ventures sound like logical extensions of existing media brands because, afterall, media companies are all about attracting and keeping audiences and then figuring out ways to bring them closer to marketers.

Know this: if you are part of the social networking wave, you will have all the “friends” you can handle. The invite is the new handshake. Get ready for a lot of opportunities to join all kinds of networks — and, one hopes, some appropriately Webby new way to politely say, “No, thank you.”

-RICHARD SIKLOS