Let me state this up front: I don't know anyone who works at LinkedIn, and I have no financial interest tied to LinkedIn becoming the next Google. I'm just a fan of the site and, more importantly, I'm a fan of the concept of a comprehensive business social network.

It all started for me several years ago when I began getting emails from business acquaintances with the subject line: "Invitation to connect on LinkedIn." For the most part, I ignored them. I spent five minutes creating a basic account and then every time someone sent me an invite, I just hit accept and never looked at it again. There was the initial wave where I got about 50 invitations over the course of a year, and then silence. For the next two years or so, I averaged maybe one a month.

But something happened in the spring of 2007. I started getting invitations more frequently. By July, I was getting several a day. LinkedIn was catching on and starting to become a standout property. It was beginning to cross the chasm that separates websites. There are plenty of trendy concepts that get a little love from the tech blogs, but only a few transcend into the mainstream. We've seen it happen with Google, MySpace, YouTube, Facebook and, most recently, Twitter. LinkedIn is headed in that direction but hasn't completely become ubiquitous -- which is a good thing. (For the moment, the porn purveyors haven't mastered LinkedIn!)