For all of you who still have difficulties in distinguishing Usability from User Experience, there is a great post (in German language) on the uxzentrisch blog that is a follow up on two sessions of the UXcamp back in May this year. Tobias Jordans compares two opinions, which he collected in video interviews: at first the virtual keynote from Jesse James Garret that they showed at the UXcamp, and second a follow up interview with Knut Polkehn to his session “What the heck is Usability?”.
Both conclude that Usability is a part of User Experience, because User Experience includes more aspects than just the usability of a product. What I liked in Knut’s conclusion is that he does not care that much of the concrete terms but sees the similarities in both approaches (Usability Engineering vs UX Engineering).