It would be very useful to be able to make branches from the main website for larger projects.
Sometimes customers (and ourselves in house) want to refrain from making work live but want to make smaller, more urgent fixes.
This can be quite tricky sometimes as there can be a lot of tricky conflicts such as stylesheets being many version ahead, content on pages not existing anymore, layouts that are used for multiple pages etc.
Additionally, js and xslt files that are used are not version controlled so multiple versions of these files need to be created in filecache to accommodate this, which is not ideal.
I think having a release process and version control simliar to out core product would be really useful.