Highlights of this new release include software metrics, project mess detection, copy-and-paste detection, improvements to SeleniumTestCase for better integration with Selenium RC, data providers for test cases, and grouping of tests.

Another mentor for another Google Summer of Code project has been announced and Sebastian Bergmann will be mentoring Mike Lewis as he adds mutation testing for PHPUnit.

Sebastian quotes a definition of "mutation testing" as:

Mutation Testing, or Automated Error Seeding, is an approach where the testing tool makes some change to the tested code, runs the tests, and if the tests pass displays a message saying what it changed.

The key difference is that it makes it easier to run a series of tests rather than just one at a time, aiding in more complex testing abilities. Check out this page on the PHPUnit site for more information.