The search should be smart enough and show boxes: 1. Tags found 2. users found 3. content found etc. Or some according checkboxes to filter results.
"Normal" users will not know about this "tags:"-feature, and even if, they would probably not use it. So it's more for us pros :)
PS: Most users don't even know that you can filter searches in google with "filetype:pdf" etc.....