The article that the author links to[1] is talking specifically about unit testing in Java. I'm not sure it has ever been that popular in Java to begin with, although there may have been buzz about it for a while. The arguments for its waning hinge on the idea that unit testing is hard and requires training and books. Refactoring legacy code for testability can be tough (or at least scary), but writing unit tests themselves is pretty easy, and questions about how JUnit works can be answered by a web search.
This hasn't been my experience at all in my own work. While I don't subscribe to the extreme 'unit test every single function' mindset, I definitely find unit testing to be useful for checking the consistency of key functionality on a per-module basis. And that has the bonus side-effect of ensuring that I keep the code structured in easily-tested modules with well-defined interfaces.
[1] http://binstock.blogspot.com/2008/05/is-popularity-of-unit-t...