T.H.
I am teaching my daughter to say excuse me and wait patiently if I'm talking and there is no emergency (Catwalk's story was funny!), but it's super hard for her, it's a long process. However, if she's trying to listen to and/or participate in an adult conversation I shoo her out of the room and tell her to go play. I send the message this is for adults only and I will stop talking and wait for her leave. Personally I don't think enforcing a 'speak when spoken to rule' is appropriate, but she just needs to understand that there is a forum for her thoughts and opinions and then there is not. :)