Replying to Can you find a stolen phone using google latitude?

My boss's phone got stolen last month in Big Bear, CA. Today (3 weeks later) the phone pinged on google latitude from Michigan. Does anyone know if the phone will ping every time they use wi-fi and is there a way for me to track it? If I can contact the person, I want to offer a reward to return it because we don't want to loose all of the contacts but I don't know if there is a way to do this... any ideas?