I was at the Vancouver Comics Fan Expo last month and I would say the attendees were 50/50 males and female as well. I might even say that the females might actually outnumber the males, it seems like every girl brought all their female friends to the expo. Now I no doubt believe that a large majority of them are there to see their favorite tv and movie stars but I saw a whole bunch of these young girls buying up independent artwork and comics. There was so much a variety of different genres that there's something for everyone. I went to a Q&A panel with Mark Bagley and there were tons of girls there too. This was something I never saw growing up.
I do have one beef with this Fan Expo though, I'm not sure if it's the same for every where else. Overall it was a positive experience but I find that the comic book vendors there were price gauging the attendees, everything was really marked up for outrageous prices for the expo. This was my only complaint. From talking to some of the regulars at my LCS they felt the exact same way that the comic book vendors specifically were taking advantage.