Denny and Drew:
I just listened to the question on the podcast about the guy that was having trouble carbonating his coffee beer and have an observation/question on this.
I once had this problem with a porter when I was doing extracts years ago and one of the local guys that was a homebrewer, (he was also my boss during my radio career life) mentioned that it could be a low protein level in the beer that could be preventing proper carbonation. I have never researched this more and took his word for it since it sounded plausible. The more I thought about this after hearing this question, I wondered about CO2 dissolving and being held in solution in the beer by protein molecules. BTW, it has never happened to me again. I too do not think that it is the oils from the coffee.