I have used PHPUnit heavily now for the last 4 years. As anyone that is heavily involved in writing Unit Tests knows, test doubles (commonly referred to as mock objects) are a necessary part of your toolbox. The mocking options that we used to have for PHP unit testing have traditionally been fairly limited and most all of them in some form or another were ports of JMock. The way PHP operates as well as some decisions made to more closely emulate how JMock does things lead to functionality in the existing mock library for PHPUnit that for some are a hassle.
To help eliminate this hassle, he create the Phake mocking framework - a tool that comes at mocking a different way than the normal PHPUnit procedures. He includes some sample code for a class to test, a simple stub for getting a value and how to use it in a basic test. By calling a "Phake::mock()" on the class to make an object, you can call the method and run a "verify()" to ensure that the results are correct. He talks about some other options that the mocking allows too like calling a "no interaction" method on a mock and argument capturing.