It seems very unusual but there are many cases and one came on CNN today. There are few cases in Washington, Illinois and Michigan.
A man in Michigan is facing felony charges along with penalty for using a Cafe's WiFi internet sitting in his car outside the cafe. He is being termed as "WiFi Freeloader", accessing computer network without authorization.
I am just remembering those days when I used to use my laptop connect to anyone's wireless network in my neighborhood for internet access. It looked very easy and cost-free .... but never knew it is a crime.
Be careful folks.