I have to deploy my php/html/css/etc code to multiple servers and i am looking at my options for software that allows easy and secure deployment to multiple servers.
If you're running on Redhat or Debian, consider packaging up your code into RPM's or Debs. Then build a yum or dpkg repository and put your packages there. You can then use your system's package management to do upgrades/rollbacks, etc. You can even use puppet to automate the process.
If you want to tie it into subversion, you can create a branch for each new version. Use the commit scripts to build the RPM's when a new branch shows up in a directory.