Graham Glass mentioned opt-in vs. opt-out organ donation and I went looking for the North Carolina Drivers License forms because I was pretty sure North Carolina was an opt-out state, that is you had to check a box to not participate. I never found the forms, but I did find this Press Release:
Governor Easley has signed a new law that will convert the existing heart symbol on the driver’s license to legal consent for organ and eye donation. Previously the symbol signified only the intent to donate.
I've lived in North Carolina for 15 years and every time my license has come up for renewal I've made sure I had the little heart on my license, thinking that was all I needed to do. It turns out that up until last September, I was wrong. Glad they finally got that straightened out.