Clear segregation of dev/authoring + live/production environments for modifications in templates

Use case: IT team working with the Business Lines/Editors to add some enhancements to the current site (e.g: add some commentable areas in certain templates, some tagclouds, etc...)

I then have an ACME site which is already published. From the Studio, I emulate the IT dept bringing to the editors the changes they want on their site. Hwoever as soon as I deploy the templates, the live environment is immediately impacted without any further workflow.

So how can I create an easy workflow from IT Dept to Business Lines to Production Environement (or from the development studio to the wireframe/mockup mode for the Business Lines to the live published environement)? Shouldn't there be at least a validation workflow by the practitioners/business Lines/Edit mode before final approval of changes in some templates?

More globally, this raises the question of the flow of communication/validation between the IT team which has access to the Studio and the Lines of Business which have access to the Edit Mode and how the system improve communication and productivity among those two groups + who is finally responsible of the live published sites