Now this is huge, and probably in response to MSN's adCenter.
SEW has the scoop at http://blog.searchenginewatch.com/blog/060308-200902
Gender, Age, Income, Ethnicity, Children.
It is worth noting that the AdWords demographic offerings are much more detailed than what adCenter offers. Presently, adCenter allows demographic targeting by gender and age group, however adCenter splits age between five age groups while AdWords offers six. Both also offer regional targeting, which adCenter has within their demographic options.