I just read this blog post - http://blogs.bnet.com/career-advice/?p=1310 entitled "Do I need a LinkedIn Profile?" by Suzanne Lucas.
She referenced some interesting points about recommendations and your contacts.
In short, she said, the worse the employee the shinier the profile. Is this true??
Another point she made was that recruiters may delve into your profile, find contacts with whom you may have worked and start making contact with them to find out about your work habits and ethics. In other words, if you are connected with co-workers that you had at a former employer, you need to know what they have to say about you as well as the people who have actually recommended you.
This is the same as knowing what a potential employer will find if they google your name. Be aware of your personal and professional reputation.