Sebastian Bergmann has pointed out something obvious to anyone that's ever tried to work with unit tests in PHP - there's just not that much support for it. The software is there and waiting to be used, but too many developers just don't take advantage of it.
Maybe it took the PHP community a little longer to realize the importance of testing. But now that we know how to build applications that "just work", are fast and scalable, as well as secure, a big topic in the PHP community right now is to implement processes and use techniques that help us assure that the software works correctly throughout the its lifecycle.
He points to some comments made at a recent panel discussion about PHP and testing, the proliferation of frameworks for the language and the things that have no name that developers use every day to make their code "just work".