Women speakers at tech events

I'm in the process of sorting out the interactive media placement. A friend of mine pointed me to Jason Kottke's blog where he lists the number of women speaking at upcoming web/tech conferences - the average proportion of women speakers seems to hover around 15 per cent and some conferences have the audacity to list 0 women speakers. I agree with Jason, it's laughable in this day and age that conference organisers can't find dynamic, observant, entertaining female contributors - but, sadly, the average figure must more or less reflect the proportion of women working in top jobs in the industry.