After the 1.5 release we moved our source control off of the legacy Sourceforge CVS system and on to a modern Subversion repository. When we get confused about Subversion we use this great Subversion book that's available for free online. Here are some quick tips for checking out and working with the WordPress repository.
This all assumes you have Subversion installed on the machine you're working on. If you don't, check out the links above.
To check out the latest WP codebase, try this checkout command:
svn co http://core.svn.wordpress.org/trunk/
This will "check out" all of the files you'll need. To update your working copy later, go into the directory and run this command:
And this will output a line-by-line description of all the changes in a format that makes it easy for us to incorporate:
You can output this to a file (.diff or .patch) by using redirection:
svn diff > my-patch.patch