This feature allows you to right click on a cube in an Analysis Services solution and deploy just the calculation script.
You can also deploy the MDX script by clicking the button in the toolbar above the calc script:
Note: This feature is not available when editing a cube in online mode as there is no need to deploy when you are working in online mode.
Note: To capture the XMLA *BI Developer Extensions* uses to deploy the MDX Script (so that you could deploy to a different environment without SSDT) see this blog post.