If you are interested in testing and the TDD/BDD movements, then you may find presentation on "Story Driven Development" worth watching. Bryan explains the differences between unit testing and scenarios. He also shows Webrat, a tool he works on, which makes defining stories in Rails apps very easy.
I like the title that Bryan has chosen for the talk. The name "Story Driven Development" makes it clear that it's a lot about defining requirements, and not only about testing. Additionally, I think it's clear that it focuses on the acceptance level of tests without mentioning unit tests.
He also provides a quote from Robert Martin:
Unit tests: “Make sure you write the code right.”
Scenarios: “Make sure you write the right code.”
You can watch the slides here, or grab the PDF version (which has correct code examples).