Not much time right now, but I've just read:
http://www.infoq.com/news/2008/10/iterating-for-knowledge - which is about iterating for knowledge, which I think is as important as iterating for business value. Both have their place, but I know it's a good idea to allow knowledge gathering. After all, the idea of just getting the project out the door with little or no effort, seems a great plan, but could lead to frustration in development teams.
I've not had a chance to go through: http://www.acceptancetesting.info/resources/ yet, but it looks quite interesting as it cover a lot about agile acceptance testing.