Gamasutra reports on a study on games from Australia:

The report, which was issued by the IEAA (Interactive Entertainment Association of Australia) game industry association, was based on data compiled by the Bond University Centre for New Media Research from surveys of about 1,606 households and 3,386 individuals. Of those individuals surveyed, 41 percent of the respondents were female (up from 38 percent), while 8 percent were seniors over 60 years old. The oldest gamer surveyed was 84 years old.

Lots of interesting charts and stats in the study itself. The Gamasutra article mostly just digests it.