Power, to most women leaders, is horizontal — about influence across many areas. The careers of successful women tend to be less vertical than a ladder — more like jungle gyms. Many women I know who have reached the top — the top 50 in business, according to Fortune‘s annual Most Powerful Women list — have moved laterally, even moving down a notch, to broaden their experience. Peripheral vision is key. Smart women swing to opportunities, over here or over there — maybe after time out to raise kids and build a full life along the way.

A new book called Womenomics captures a lot of my thinking. I have nothing to do with the book, though I know Claire Shipman and Katty Kay, the co-authors. In fact, they’ll be speaking about their research and insights at the Fortune Most Powerful Women Summit this September.

Yesterday Jessica Shambora, my Postcards colleague, and I subwayed downtown to hear Shipman, who is senior national correspondent for ABC’s Good Morning America , and Kay, the Washington correspondent and anchor for BBC World News America. They talked about why companies should work to keep women leaders: mainly, because businesses with lots of women at the top perform better. Several studies prove that.

The best stuff that Shipman and Kay shared was about how successful women behave and how smart managers respond. A few nuggets from their talk:

Time is the currency for women. “We’re prepared to trade income and status for time,” says Kay, a mother of four. Both she and Shipman, who has two children, have made that trade in their own careers, passing up promotions — even though women (and men even more) fear the public perception from ratcheting back their ambition. Sara Lee CEO Brenda Barnes, who took her own multi-year timeout from a big job after scaling the ranks at PepsiCo , told the authors that now is a prime time to ask to work less, if you so desire. Why now? Because many bosses are looking to cut costs without laying off people. Notes Kay, “If you look at demographics, there’s a labor and talent shortage looming, so they want to keep you.”

Enlightened companies treat employees like grownups. The real forward-thinking companies encourage employees to get their work done wherever, whenever. “It’s not about face time or office time,” says Shipman. “It’s about what you produce.” She and Kay mentioned Best Buy , which “abandoned the clock” a few years ago. Giving employees the right to work on their own time and own terms — with clear targets and measurement systems to monitor them — boosted productivity dramatically.

Know yourself. As companies squeeze costs, do more with less, and pile the work — on you! — you need to know what your true value is. “Have the power to say, ‘This is what I can do for you,'” says Kay. She and Shipman lay out ways to appear as if you’re saying Yes when you’re actually saying No to an extreme assignment. Say you can’t possibly finish that report by Friday. You might tell your slave-driving CEO or supervisor: “I’m happy to take this on. I can have it to you by June 27. Do you want me to bring someone else in so we can make an earlier deadline?”

Indeed, in these stressed-out times, when most of us are questioning our jobs and our careers, it’s critical to know what you’re best at and what your priorities are. For more, check out this “Know Yourself” post that I wrote two months ago. And when you have a moment to breathe, check out
Womenomics
.