welcome to WB. Nice to hear that you love WB.
I want department heads to be able to write and change their content, but I'd like to review it before I choose to publish it. It doesn't look like that system is available in WB.
You are right, that is not integrated in the core at the moment. But there exists different workaround how to solve this.
One option is to have two wb installations in one database (works with different table_prefixes). One page is the live site, and one the dev site. The departemensts only work on dev site and you set them after prooving to live. Issue it only works to set the whole page live not especially parts of the page.
Another option is to use a advanced version of WYSIWYG of thorn. with this it is possible to make a working copy of a page, where changes can be made, and as soon as they are ready they can set to live. This tool also holds all old content wich can be set back to life with one mouse click. Issue of this tool is that there is no difference between the people who work on pages and admins who can set it to live.
So you see we are working on it, and I'm pretty shure in one of the next version we will have ot working that only admins can publish pages.