If you’re an average WordPress user running WordPress to power your site, you’re probably going to want to stick to working with the latest stable version of WordPress.
But if you’re a Power User, or WordPress theme or plugin developer, you’ll be happy to know that you can get ahead of the game by running WordPress “trunk” – the bleeding edge version of WordPress which features the absolute latest code changes implemented by the core WordPress team. You should NEVER run this on a live site since it’s not close to a stable version. You SHOULD use this environment to test your code against future releases of WordPress and prepare accordingly.
The WordPress core team uses Subversion as their version control system, but these days the trend seems to be toward using GitHub as a repository so that’s what I’m using in this example. The WordPress GitHub repo is a mirror of their Subversion repo and is synced with Subversion every 15 minutes.
There’s several ways to go about running WordPress locally and connecting to either the SVN or GitHub repos – for me, this was the easiest to set up and can be done using free tools (bonus!) which are both PC and Mac friendly.
Read full article at Run a Local Bleeding Edge WordPress Environment – Media Temple.