What happens in Illinois if you a person of 17 years of age commits a misdeminor in Dec of 2009 but does not have a court date until Jan of 2010 after the age of Delinquincy is raised to 17 on Jan 1?

You will be tried under the law that was in effect at the time you committed the offense. To do otherwise would expose you to an ex post facto situation which is expressly prohibited by the US Constitution.