On the KillerPHP.com website today, there's a good beginner's guide (from J. Lenensold) about using version control in your development - specifically Subversion.
As projects start to get a little larger, it becomes crucial that you manage your code in an easy and organized manner. Using subversion is a breeze with tools like TortoiseSVN on windows and SCPlugin on the mac.
This article is an attempt at introducing the concept of SVN. There are many great tutorials out there that outline the steps for installing SVN on windows, mac and linux.
He talks about why using version control is a good thing, how it can speed up testing and even relates it back to PHPers with a sample workflow (with graphic) and some helpful hints as you introduce this very handy functionality into your development process.