Congrats to CollabNet! Subversion, the open source versioning tool written as a "compelling replacement to CVS", was named by developer.com as the Product of the Year 2008. We've been using subversion for our work for over a year now and its proved to be a very useful tool in helping us get work done and be more productive.

Before SVN, we had a manual cut over process to move files from our development server to production servers. It was slow, since you had to navigate around the file system, and error-prone, since one could never be sure that you moved all the correct files. This became more of a problem as multiple developers and designers would work on a single site. Now, SVN is constantly keeping track of which files are modified on each environment and automatically synchronizes the code on each. It's also allowed us to move from a single, shared development server, to working locally on our own workstations. We've also started exploiting the hooks in svn for checking PHP syntax before commits, and sending emails for code-reviews upon commit.

If you're working with or hiring programmers, one of your first questions you should ask them is how they manage and track changes to their source code. If they aren't using subversion or another system, that's an immediate red flag.

We've written about subversion before. Dan's previously written about Subversion: Simple Practices and Sandy wrote HOWTO: Use Eclipse PDT with Subversion in 13 Easy Steps.