Users are filling in many informations about themselfs in their profile, either by way of an AD or LDAP, or by manually editing it. They may be using add-ons like Linchpin Profile, as well, granting even more depth and detail about who they are.
Showing or hiding information based on profile data would allow some way of personalizing pages and contents for users, thus adding significance and relevance. Example:
Multilanguage blog posts: Imagine a space with content in 2 or 3 languages; while pages can be handled with add-ons like Translation for Confluence, there is no way to do this gracefully for blogposts. Therefore I would go about this in such a way: