While I do understand 6 pack abs aren't definite goal for every women, it's not impossible for every women either.
I'd like to start a discussion so that we can create
http://www.scoobysworkshop.com/HowLongToGet6packAbs.htm for women.
Scooby provides lot of useful information but not all these are applicable to women. With your experiences and expertises, I'm sure we can create one for girls

1.To have abs, you need to get down to
about 7% bodyfat. Calculate how many pounds
fat 7% would be.
I guess it's around 20-18% for women. Some can go less than 18% but never less than 13%. Reducing less than 13% only risks our periods, immune system and overall health. And you'll have flat chest :'(
http://www.acefitness.org/blog/112/what-are-the-guidelines-for-percentage-of-body-fat/2.Calculate the number of pounds bodyfat you currently have on your physique using my
body composition calculatorUnfortunately Scooby's calculator for women doesn't exist yet. But I don't think we need to push Scooby. There're still other ways. US Navy method is enough accurate and impedance method is some what unreliable but better than nothing.
http://www.wikihow.com/Measure-Body-Fat-Using-the-US-Navy-Methodhttp://www.linear-software.com/online.htmlAnyway, know your BF number and then let's calculate how long.
3.
http://www.scoobysworkshop.com/caloriecalculator.htmI was 45yrs old, 159cm tall, 60kg, 20kg fat, 33% body fat on Jun 2010. To get to BF, I had to lose 12kg of fat, and to be 50kg/18%.
According to Scooby's calculator, with 20 calorie reduction and 21 hour exercise per week, I could lose 1.8kg per month and 6 months were enough. In fact, I got 50kg/18% in December 2010.

photo

weight/bf progress
Resolution: Lose Weight And Get In Shape!
During the 6 months, I faithfully exercised Scooby's resolution, did cardio every morning for one hour, brisk walk outside, strength workout every other day, and ate 6 well portioned meals. I started to see the difference in October, after 4 months, that I could wake up in the morning on time and enjoy the walk. And I could do unassisted pullups.
After that, everything has become so easy that workout and 6 meals are nicely incorporated in my everyday.
I do some weight lifting now but mostly calisthenic workout and I practice bouldering 1 hour a day or so.
What's your story and what do you think women need to get 6 pack abs??? Thanks!