What is LinkedIn?

LinkedIn is a popular social networking website primarily used by an audience of professionals and business people.

How to Use LinkedIn:
LinkedIn is a membership-based (it's free to join), no-frills social networking site with a reputation of being the place to network for career development and job searches. You cannot view another LinkedIn member's profile unless you are connected to that person, and you can only get connected if you know that person outside of LinkedIn already or if you are introduced to that person.

LinkedIn for Blog Promotion:
LinkedIn is best used for career networking, but that doesn't mean you can't use it to promote your blog content, too. Spend time making connections, answering questions that people pose through LinkedIn and building relationships. Be sure to create a complete LinkedIn profile and include your blog's URL within your profile. As people learn who you are through your LinkedIn connections, chances are they'll click on the link for your blog within your profile to see what you have to say.

Bottom-Line:
LinkedIn is one more place where you can post a link to your blog and develop relationships with people who might be interested in reading your blog content. While it is unlikely you'll gain a big bump in traffic after you join LinkedIn, the relationships you build through your LinkedIn connections will drive indirect traffic over time.

Taken from: Susan Gunelius, About.com Guide