(Editor’s note: Joyce Park is founder and chief technology officer of Renkoo, an event Web site we will be hearing more about later at VentureBeat. Joyce has written a piece below about female leaders in Silicon Valley and wonders whether female power at Google may be a sign of change — or not)

Rolling up to the supermarket checkout line this weekend, I was stopped dead in my tracks by the Newsweek cover of Patricia Dunn, HP’s embattled board chair. Except for Steve Jobs, you actually hardly ever see a Silicon Valley denizen on the cover of a checkout-display magazine; and Ms. Dunn’s tense expression in unflattering extreme closeup was particularly glaring when surrounded by the glossy photos all around:

Jessica Simpson, mouthwatering food, guys with six-pack abs, and Oprah at her most nurturing-looking. My stomach actually sank a little as I put the magazine in my basket, and I can’t say I enjoyed reading the story inside. Since then, not a day has passed without its own revelation of further dirt done by HP’s board.

It’s easy to take the narrow view and say simply that Carly Fiorina left a crater for Silicon Valley’s female execs, and Patricia Dunn — aided and abetted by her female corporate counsel, Ann Baskins — fell into it. But it’s hard for a woman in the industry not to feel a stirring of glum dread looking around at our leadership these days. Ebay’s Meg Whitman no longer bounds from one stock high to the next. Carol Bartz of Autodesk recently stepped down as CEO. The ugliest venture capital scandal of the last year involved a female VC at VSP Capital.

There are few terms more abused in public life these days than “role model”, of course — I always admired Charles Barkley’s take on the subject, and certainly none of these women could be said to overtly have volunteered for the role — but like it or not they enter into the calculations of many women below them. The truth is that ambitious women in this business always have to be figuring the odds, and high-profile female execs are the data points with which we do the math about the possibilities. When other women seem to be kicking butt in their roles, then the odds — however slim — seem to be better. But when the number of successful women in the top tiers of the tech business appears to decrease… possibility itself seems to contract to the size of a theoretical particle. There’s a world of difference for me and my friends between “theoretically possible to succeed as a woman in this business”, and “lots of women have done it, maybe I could too.”

Perhaps surprisingly for such a famously objectivity-loving company, the brightest hope for Valley women at the moment comes from Google. The number four person there, behind only the holy trinity of Larry, Sergey, and Eric, is the relatively little-known Shona Brown. The next tier of VPs boasts even more female star-power, including Marissa Mayer and Sheryl Sandberg. Google has also been extremely supportive of female engineers at all levels, especially in partnership with the Anita Borg Institute for Women and Technology (for which, full disclosure, I am a very low-level advisor). What particularly impresses me about Google’s female leadership is that they are extremely operational — not just relegated to the HR, finance, and marketing jobs that can hamper women who hope to run technology companies — but also surprisingly young.

Perhaps this indicates that the next generation of women will have an easier time being integrated into the heart of Silicon Valley’s value-creation machine. Or maybe it just means that Google’s female leadership has yet to meet the challenges of marriage, parenthood, illness, and burnout that appear to have derailed so many older female execs on their march to the top.