Good question.  I know we can change the name of sites via the admin UI.  But can we use tabadmin commands to change, for example, logos and names based on sites? 

Unfortunately, this is not yet possible in 7.0. This is a feature that we look to be adding for v8.

Does anyone know if these ever made it into the Product? I'm here using Tableau Server 10 and can't find a single resource that mentions branding each individual site on a Tableau Server instance.

Found a resource here after combing the Community pages: https://community.tableau.com/ideas/5837 -- vote up on this idea if you want this feature.

It has not made it into the product.