I have heard one too many times of a landlord wanting to keep someone's security deposit. By law, if you haven't ruined anything at the unit, you're entitled to it back. They can't just keep it for normal wear and tear. But sometimes the landlord needs a little nudge. By law, just asking for your deposit back won't guarantee that you'll get it. You must put it in writing.
Also, if you have any questions about the landlord/tenant act, you should call Metropolitan Fair Housing Council at 232-FAIR. I call them whenever I have a question and they're very knowledgeable on the law.