I also got the impression that there isn’t a great deal of difference – semantics aside – between the user story and the use case scenario.

I’m admittedly more a student of agile methods than a practitioner. I’ve read the books,the articles and the blogs and have participated in a few quick projects that were termed “XP” or “rapid development”, but have never worked extensively in what purists would consider an agile environment. I do have to agree that, regardless of the methodology, tossing documentation that represents important decisions and rules seems like risky business.

As for the “torn up and thrown away” part–well, I have yet to find a place where this actually was OK in real life. Almost every Agile project I’ve encountered ended up requiring a major documentation effort after the project wound down and the business owners started to realize that the only people who knew how the system worked were leaving.