Parents are surprised to hear I recommend high school students ages 16+ create a LinkedIn account. I'm always proud of young adults when I speak at HS's and ask if they are on LinkedIn and they say, "Yes!" They have smart educators who know the value and are giving them a jump-start on their professional networking. While attending a college admission conference last year, universities talked about how they are allowing this to be part of their application process. I believe resumes will go away and will be replaced with the ability to link to your LI profile.
As a result, I saw this outstanding article by Socially Savvy that I felt was worth sharing. It outlines why secondary students need LinkedIn. If you want to stand out from the college competition, this should seriously be considered.