Living wills have been around for a long time, but most people were very careless about creating or maintaining these essential documents. That changed in 2005 due to the highly publicized Terry Schiavo case. Since that time, many people have created living wills - often through forms they've been given by friends, their church, or that they've found online. If you have a living will made through any of these forms, and something happens to you, the hospital caring for you (and if necessary, the courts) WILL try to honor the wishes expressed in those documents.
But you shouldn't have a living will at all.