Lead Designer at Viddler, Andrew Smith, has released Pack via the Viddler blog – which is what he uses to compress Viddler’s CSS and Javascript for deployment.
Pack is written in Ruby and runs from the command-line. However, you could easily daisy chain it to Capistrano when doing deploys, like Andrew has done for Viddler, to make it one less step to deploying code that is optimized for page load.
Oh, and his post includes a cat. So there’s that.