Responding to the topic at hand: The amount with which I'm open about my atheism depends on the context. My immediate family is well aware that I'm atheistic. My father's and step-father's side of the family are completely unaware as far as I know (which is to say they don't know given that they're extreme bible thumping Christians to the extent that one said before the last election, "I hope Bush gets reelected so he can put an end to all those homo weddings." If they knew, they'd try to re-convert me.) In my professional life, I just make it a non-issue. In teaching college courses I avoided the issue whenever possible and when I was forced to mention it, I only gave quotations and informed opinions of others from both the theistic side and atheistic side so as to not reveal my own standing. In the semi-inbetween realm of being a science blogger, I wear my atheism on my sleeve as it were as it's one of my main topics.