No offense soccerchic, but I think you haven't investigated the AF world very much.
http://www.seymourjohnson.af.mil/library/biographies/bio.asp?id=15663
In case you don't want to read it, she is the 1st female fighter pilot, and now the 1st female wing king of a Combat Wing.
Here's another:
http://en.wikipedia.org/wiki/Nicole_Malachowski
FiFi flew the Thunderbirds and with the Chiefs or Rockets at SJAFB operationally, she is now a squadron commander in charge of ALL FTU students in her squadron.
Back in 98 when I was getting my Masters, my thesis partner was an ABM member, a SHE!
This law may be new for the Army, but it is @ 20 YRS OLD for the AF. That ceiling was busted through before you were probably born!
The way AFROTC works is you apply rated and Pilot, CSO, RPA and ABM are your options. Highest OML wins.
As a woman, the only issue compared to men will be your sitting height. Nobody cares about your sex in the AF anymore. It is old hat now.
To add onto kinnem's post regarding the amount, I would say it is equivalent to the male/female ratio in the ADAF. I can't recall a fighter squadron since 97 that there wasn't a female or two in the squadron.
In the end, if you want to fly combat in the AF there are probably 100-200 women in front of you that are flying have flown combat missions.