Interesting, AG.
I'd say what you describe, is not so much boundary setting, as tactfully managing the conversation.

verbal boundary setting, is for those of us who are not so skillful at on-the-spot wordsmithing, I think ;\)

AAAANd... i gather that you are female \:\) females are usually better at conversation manipulation, whereas us males more often have to resort to more blunt tactics \:D
(you have 20% more verbal related brain area or something, after all)

I know that I personally tend to be waaay more articulate on the boards here, then when confronted by my wife in an "immediate" conversation.
I can always think of great ways to respond.... a few hours after the conversation is over and done with \:\(

My current status: june 2006. Wife ran out and filed D.
Finalized Jan 11, 2010, after 12.5 years M.
3 wonderful sons caught in the middle