...Google Stats? I don't have an appropriate name for them but check out this query. http://www.google.com/search?hl=en&lr=&c2coff=1&q=%22California+Population%22 It'll spit back the population of the state as the top reference and where it obtained the data from. I wish I had this kind of stuff when I was in middle/high school
For further reference: Slashdot article on Google Factual Answers Something of interest is where will they be getting the data from, since it's presented as an "authority" answer. I'm guessing wikipedia for a lot of things given their sponsorship, and other big PR sites.
It'd primarily be Wikipedia I take it. That's part of the reason why they've invested in them since their goal is to organize the world's information and make it easily accessible by all.