I'm an elementary school teacher originally from California. I'd never heard "on" used with "today," "tomorrow," or with "yesterday" before I moved to Houston, Texas, where I live now. I hear it daily, by people from all walks of life. My school's administrators say it during morning and afternoon announcements. It hurts my ears. It bothers me that the kids hear this as a model for "proper" English. But, seriously, how do I bring THAT subject up with an administrator?!