WordPress, by far one of the most popular PHP-based applications out there has a new post to their site officially stating a change in core development practices:
In a little over a decade, we've made twenty five thousand commits to WordPress. WordPress (along with the web itself) has come a long way, but our development workflow has remained largely the same.As a part 3.7, I'll be leading an effort to revamp and streamline our development workflow. We're going to bring all of our core components - our code, our tests, and our tooling - under one roof. Developers will be able to use and improve the tools we're already working with day-to-day, and we'll be able to add new tools to make working with WordPress even easier.
We're also making sure that any changes are compatible with our current workflow, so you won't have to change the way you work. These changes won't break any existing checkouts or scripts that use core.svn.wordpress.org.
The post also details some of the new things they're doing to improve the development and deployment process. This includes the creation of a "develop.svn.wordpress.org" SVN repository to hold all new WordPress development. There's also a new build process involving a tool called "bumpbot" and the new addition of Grunt.