Many of Fortune's Most Powerful Women -- a group we've tracked since 1998 --  contend that corporate America will have parity at the top someday.

No way, I say. It's not that the glass ceiling won't shatter. Indeed, this year's MPWomen list, released two months ago, has more Fortune 500 company CEOs in the top tier than ever. But as I've overseen the MPWomen franchise over the past decade, I've gotten to know these top women leaders. And I've learned that they're a rare breed, unlike most corporate women on the way up.

The gist of women and power: Most women view power horizontally: power is about influence more than about rank. Women also tend to view their lives in chapters. So many drop out early to do other things. Look at Meg Whitman retiring from eBay (EBAY) at 51 and now considering politics -- a run for California governor, perhaps?

So it's not terribly surprising that Catalyst's just-released study on Fortune 500 corporate officers reveals that only 15.7% are women. This is scant progress, since 15.4% were female in 2007. But there is one place where women practically rule: Edison International (EIX), the California-based utility, where fully half of the 14 most senior corporate officers are women. Next on Catalyst's 2008 list: Dollar General, now privately held by KKR, and Kraft Foods (KFT), Northeast Utilities (NU) and Reynolds American (RAI).

A few other companies on Catalyst's list happen to be represented on Fortune's Most Powerful Women list: Both Western Union (WU), led by CEO Christina Gold, and Avon (AVP), where Andrea Jung is chief, have women holding at least one-third of the most senior officer positions. As does Johnson & Johnson (JNJ), where Sheri McCoy is the rising star to watch. In October, she got promoted to worldwide chairman of J&J's $25 billion pharmaceuticals group and may be a contender for CEO someday.

Which Fortune 500 companies have no women in their top officer ranks? Catalyst lists Apple (AAPL), Dell (DELL), McGraw-Hill (MHP), TRW (TRW), Whirlpool (WHR), and Winn-Dixie Stores (WINN), among 69 others. As my colleague Jessica Shambora noted on Postcards on Wednesday, how can retailers and other consumer companies thrive without women executives contributing? Apple seems to have no trouble with all guys in charge.  Steve Jobs did, though, add a woman, Avon chief Andrea Jung, to his board in January. Smart guy.