It is impossible for the sites to do this. There is no way to independently
identify the age and identify of minors. There is no RealID system for
minors! More on the infeasibility here:
http://cyber.law.harvard.edu/research/isttf
Seems to me to be a major opportunity for Illinois high school educators to
get your students involved in learning about the legislative process.
My perspective is that the only reasonable option for Facebook, MySpace and
any other social networking site would be to terminate the accounts of any
minors who live in Illinois because it would be impossible for them to do
this. The penalties for non-compliance would be pretty tough. Many
co-sponsors. You might want to alert your students. They are the ones who
would be impacted.