I think this is really great, and a big surprise. I expected the number to be much lower than what it is. A study conducted by Nielsen Entertainment showed that 64% of online gamers are woman. Also, about 8% of that are woman who are at least 45 years old.
The study doesn't stay what type of games are played, so it's assumed that this also includes flash based games as well. So if any of your are on Xbox Live be sure to look me up.