Are Testers eXtinct? How Can Testers Contribute to XP Teams?

There are lots of success stories for XP teams where testers made a significant contribution. There are lots of success stories for XP teams that didn't have an official tester. There are some horror stories of so-called XP teams who didn't have testers and didn't do a scrap of acceptance testing. As more organizations try XP, there are a lot of teams out there wondering if they need testers, and a lot of testers who are suddenly members of XP teams wondering what the heck they are supposed to do. This is relevant to anyone on an XP team, any QA / test professionals who are interested in doing XP, anyone in a software development role who is considering using XP. The current Extreme Programming publications don't really define how an XP tester can contribute to the project. What should testers do? When should they do it? How should they do it? Is there even a place for testing and quality assurance professionals on XP teams? Can any tester be an XP tester? See http://www.testers.org for more information.