PHP has Phing, which is based off of Ant (from the Java world).
For Ruby, there's Rakefiles and Capistrano for web app projects. There's also Vlad the Deployer which is more lightweight. For Rails, there's a continuous integration plugin which you could use to monitor your unit tests.
If it's not a large project, you might consider just writing your own tasks to automate the process (ssh'in and svn up or hg pull/up). But if you need the ability to rollback or to make sure all your unit tests pass first, go for Capistrano or Vlad.
People have used Capistrano for Python web apps too.
For Ruby, there's Rakefiles and Capistrano for web app projects. There's also Vlad the Deployer which is more lightweight. For Rails, there's a continuous integration plugin which you could use to monitor your unit tests.
If it's not a large project, you might consider just writing your own tasks to automate the process (ssh'in and svn up or hg pull/up). But if you need the ability to rollback or to make sure all your unit tests pass first, go for Capistrano or Vlad.
People have used Capistrano for Python web apps too.