As a Director of Marketing at a Fortune 500 company, I feel that flexibility is the key. I have the unique perspective of being a working mother, as well as having direct reports who are moms (or moms-to-be). As a working mother at my level, I feel sometimes that the policies are on paper-only - I feel pressure if I take off to care for my child, attend a school function, etc (even though I'm on the black berry at all hours of the night, and weekends). Perhaps that's my own fault.
To try to remedy the situation, I try to provide an environment that is supportive to my working moms (and non-working moms - we have to be fair). I am flexible if they need to leave to take care of something, or need time off at home. In return, they appreciate it and always deliver for me and the company. These are smart, educated women that are too valuable to lose.
I guess the over-arching thought here is that theory must be put into practice (regardless of what level you are). If more comapnies could offer flexibility (and truly embrace it), you'd have many more happy working moms in this country.