I think a simple estimate of the composition of the "most merit of all candidate speakers" could be to compile statistics of the contributors to the 1000 most popular gems and rails-core, or something similar. There's more heat than light in this controversy, and for a discipline that prioritizes CS techniques as a proxy for skill the flashlight is readily at hand.
While I appreciate that you're looking for solutions instead of trying to amplify the finger-pointing, the approach you are imagining is not going to generate a very good speaker line-up.
There are a huge number of variables to consider when planning a speaker line-up. As I said before, the best conferences are carefully crafted around a theme or issue. Even in the case of a regional conference, it doesn't require that the speakers live nearby. Just selecting popular, smart or friendly devs is not a theme unless your theme is "Random". :)
Sometimes there's a milestone library or development approach that you want to shine a light on. Perhaps 5 of the top 10 gems are template engines or test frameworks, and in 2012 that's a dull theme. Factually, some developers are great speakers, but many are not able or willing to give a good talk. Some speakers are amazing but have nothing interesting to show off or discuss.
Some speakers live far away or have special needs. You might be able to afford and accomodate one or three, but a roster of expensive tickets would make the event lose money.
However, the biggest reason that the algorithmic curation approach is not going to work is that curation is less like selling seats on a plane and more like making a mix tape for a fickle lover. You need to delight, surprise and enrapture people. A month after the event, they remember not what was said but how they came away feeling. It's hard but worth it to find ways to inject ideas that people are not expecting.
It wasn't meant to generate a line up, only to provide some idea of demographics. You have to start somewhere, even if only to figure out how true "curating on merit gives you white guys" is.
