In NY, in particular, that seems disrespectful. If you wouldn't hold it on Christmas, you shouldn't hold it on Yom Kippur in any community that has a significant Jewish population.

Now that I think about it, it is a bit of a surprise that they'd hold it on that day, especially in NYC.

I know the organizers for NYC - I'll ask them (for my own curiosity) if attendance was down this year and if the holiday was considered. Given how big NYC CodeCamp usually is anyway, I would guess the numbers were probably not affected. But it's a good question, I can't speculate why they did it.

In their defense, organizing one that large is sometimes difficult, since the venue and date has to be planned months in advance. Sometimes the actual date isn't the first date the organizers initially wanted. Another problem is that so many MS Saturday events occur on almost every weekend, and they try not to have multiple regional events on the same day (though sometimes they have no choice).