Purdue University Physics Dept. threw another of these Physics fest this year (I reported the one from last year).
I'll say it again here. This is such a good idea. Major universities should do this often. Not only are you introducing the general public to science, you are also opening your school up to the neighborhood so that they learn what exactly it is that you do. Often, universities and the surrounding communities don't talk often, and that can create tension between the school and people who live there. Having events like this opens up the school for local visitors, especially if it is a state school that is funded by taxpayers.