Can I Trace my iPhone 4?

My iPhone 4 got stolen yesterday, I already have a mobile me account set up and have been re-trying and re-trying to locate the phone on the website but every time I do it says “no location available’’. And I think it’s because the phone was restored or turned off.

So I’m wondering is there any possible way it can be traced? For instance, can apple do it or the police? I would ask apple themselves but their customer service is closed right now.