Well, so far, I’ve had decent success talking to FireFox. This is largely thanks to the LifeHacker article by Adam Pash. If Speakable Items is turned on, it will create a Speakable Items folder for you when you open an application that you want to give voice commands to. My observations show that it can take a minute for the system to notice. (It probably depends on how many apps you have running.)
So far, I have not had success with WOW. I know it’s possible because Sean Forsgren over at Wowinsider.com has written a fantastic article on it. I don’t know for a fact, but I suspect that I have a problem becuase I am running WOW from an external drive. I will be investigating this.