I got to say that it's very different from facebook in the sense that they have a lot more to offer for the corporate world. Lot's of professional visit LinkedIn.
Yup. LinkedIn are for professionals. And Ads on LinkedIn are terribly expensive.
I think LinkedIn isthe place to be when you are looking for good business connections.
Linkedin is possibly the best social networking site for those people who're looking for work or employers looking for employees. It helps to have a profile on this type of site, because it allows you to show what you've done and be social about it. It's like your resume, but people can add you as a friend, socialize with you and so on. It's what's best for business people.