Imagine life without Wikipedia. Imagine you're wondering how a combination lock works and because there's no Wikipedia, you can't find out. Knowledge is completely blocked. You have no way to get this information. Absolutely none. Imagine a college student writing a term paper that requires citing sources, but he/she can't find any. Knowledge is completely blocked. He/she has no way to find sources to cite. Absolutely none. Imagine you're idly wondering how many different types of cows there are and what they are all called. And you wouldn't be able to find out. Knowledge would be completely blocked. You'd have to find something else to do.
I'm not against Wikipedia or anything; I think it's a great project. I'm just a little concerned that while it can be a helpful tool to find information quickly, it can also become a crutch if people become accustomed that -all- the information they obtain about anything is going to come from Wikipedia. It's also remarkably easy to waste hours wading through information you don't really need in order to avoid upcoming tasks -- there's little doubt that Wikipedia fosters procrastination. So I think the blackout is a good idea, and we should use this opportunity to remind ourselves that knowledge in pill form is not automatically power.