I recently organized a panel of MIT computer science researchers to answer questions about computer science to an audience of high-schoolers (http://web.mit.edu/cs-visit-day/qa.html). A lot of interesting discussions came out of it, and a lot to digest for panelists and audience alike.
One of the things that did stick out to me was how many of the panelists did not like their first formal training in computer science (in school, in college). I can't say I was terribly surprised, and I'd be interested to see such a survey done of the broader CS community (e.g. at a research institution) to poll about initial experiences and attitudes.
Here is where I think the problem lies: computer science courses tend to cater to a very narrow audience - maybe the type of audience that likes computer/video games, or the type of audience that likes tech gadgets, etc. Not that you can avoid it: you have to start somewhere - with some (salient) example or application or first program. But once you've settled on something, you might get one group of individuals hooked, but you'll also automatically repel a lot of other people (who are not interested in the application area you've chosen). If that was the only/first opportunity those people had to learn computer science, they might decide they don't like it and never pick it up again - which would be an enormous shame!
What's the solution? Introducing more variety and choice into the computer science curriculum - tailoring it to different tastes (and personalities!). Cater it to people who might like biology or psychology or architecture or design, and show them that computer science can provide them with a toolset, a simulation/virtual environment to test their ideas, a cool exploratory possibility. I believe this is the way forward to increasing the diversity of people in the field of computer science.
In practice, having a lot of variety in a computer science curriculum may not be possible (consider a school with a single programming course and a single teacher to teach it)... in this case, I think online education with its possibilities for individual customization, can come to the rescue... more about this later.
