PHPUnit2 and mock objects?

Hi After having done some more or less small webapps, I am going to develop a bigger one now. I read about unit-testing the last few hours and I think, PHPUnit2 is the most mature one. But what I miss is a kind of mock-objects as there is in simpleTest (http://www.lastcraft.com/simple_test.php). I read about plans to implement mock-object into PHPUnit2 on some webpage(s). I even saw a file "MockRunner.php" in the Tests directory of PHPUnit2. Is it already possible to use mock-object with PHPUnit2? Where can I read more about it? -- Cheers! Marco