I'm a bit late in pointing out this story on the National Geographic site concerning the geographic literacy of young (US) American adults. The story is cleverly illustrated with an image of the globe showing only the United States. A slightly more nuanced map of the world from the perspective of the average US citizen went around the blogosphere in 2004, before geospatial blogging caught on.
I tested myself (18 for 20), and made the common mistakes explained at the bottoms of pages 31 and 34 (see the report). There are some interesting results in there that didn't make the headlines. A majority grossly overestimate the population of the US, with 29% guessing that there are more than a billion of us! Less than 1 in 5 know that Mandarin is the most used natural language. Only 11% correspond regularly with anyone outside the US.