Automated testing is a key technical practice for agile-minded teams. Automated unit testing and testing user interfaces has been well supported for years.
Acceptance Criteria, those important adornments to user stories, however, has not been as fully supported. There is high interest and energy in this area by the community, resulting in tools and ideas like RSpec, Gherkin, SpecFlow, etc.
Come see an offering from Improving's own Ian Henehan that might be bleeding edge.