In WPMU, we are using Site Categories (with Sitewide Tags), but for the life of me I can't see how the category of the sub-site (say, departments in a school) to which each blog belongs ends up in the posts. (Well, it doesn't. I've listed out the metadata from the database and checked the post data, categories (...), terms, and tags also. Site Categories puts nothing there.)
It's probably not supposed to, but the problem I'm solving is giving posts collected to the main site an icon corresponding to the category of the site it was blogged under.
The Types plugin does this, but the category would be visible and selectable for each post the blogger posts. Instead, this value should be set to the site category once when the site is created and never seen by the bloggers.
How do I do this?
I could settle for saving an extra category with all posts on a site, but as I see it if a plugin does this it would have to have different settings on each site.