I have received a number of requests for information on how these text-to-speech blog posts have been put together.
Basically I'm using the voices from NeoSpeech and the software TextAloud from NextUp.com. You can actually purchase both through NextUp.
Previous to that, I was playing around with Babel Technologies but I think NeoSpeech is much better. Both of these however beat AT&T Natural Voices hands down. I only mention that because from what I've heard Natural Voices is supposed to be excellent but I wouldn't bother with it after hearing these ones.