The page properties are actually something that's specific to sitemesh. Very generally, I think you could use Freemarker code that looks like this to test if you're in a discussion / blog / document:
// do document stuff
// do blog stuff
// do discussion stuff
Thank you, that's what I'm looking for.
Now, is there a way to tell which index or "view" you are on, discussions, blogs, documents, all, or overview?
Nevermind, I got it: