They can find all *Test classes and run all the tests in them. Eclipse and most IDEs do this.
I am using eclipse myself and have recently begin to us the newest version, eclipse 3.2, but then do I have to run the tests class by class like applications with thier own main, did I thought. So I dived into eclipse run dialog for configuration of JUnit tests to be run and found the option "Run all the tests in the selected project, package or source folder". So yes, now I agree that I don�t need TestSuites any longer. This is even better than creating TestSuites.
But for a new practioner that takes his first look at JUnit and the documentation at their site junit.org is TestSuites the way that is mentioned on how to organize tests. So if they also had an little article like "How to organize tests" that points on the features that the IDEs offer would it probably make good. And there would probably more to say in connection to that topic any way.
Thanks for your answers! It is people like you that makes these forums as one of the absolutely best sites on the net for developers to discuss things!