Since Sass and Compass are Ruby gems, they require that you have a working knowledge of Ruby and the command line. Not all designers will know how or want to use command line tools, and that's where Scout steps in. Scout runs Sass and Compass in a self-contained Ruby environment, letting you effortlessly manage all of your Sass projects with a handful of clicks. You'll never have to worry about your Ruby setup or deal with technical issues. Scout does all of the heavy lifting, giving you more time to do what you love.
Full article: http://mhs.github.com/scout-app/