Suggestion: bundle Compass with Sencha Cmd to eliminate ruby dependency!
Now that Sencha Cmd is Ant-based, there is an opportunity to eliminate the dependency of downloading and installing Ruby and the gems required for Compass. This can be accomplished by calling JRuby from the Ant build file, and including the required gems.
To make building my app easier, I've done this in my team. Here is a link to a tutorial I followed to get this working (not my blog):
You can then integrate this into a Sencha Touch build.xml file by implementing the -before-build Ant target and making it depend on the compile.sass target described in the blog post. This will launch Compass using JRuby from within Ant.
To eliminate the dependency on ruby, you then just add skip.sass=true in .sencha/app/sencha.cfg (since we are doing the sass/compass compilation ourselves beforehand).
It would be really cool if Sencha Cmd could bundle JRuby and Compass as it bundles other tools (phantomjs, etc.) and make building with Sencha Cmd that much easier.