I just read this great post by Jimmy Bogard over at  Los Techies. He talks about user stories and the fact that what you call a user story is very important. (A rose by another other name would not smell as sweet. ) Words affect how we think about things; though we don't like to admit it.  I've definitely struggled with this myself.

If you ever communicate with your clients, then I recommend checking out the post.  It's short too.

I particularly like his comment that prioritizing a requirement is like putting lipstick on a pig.