For example, [staff]anything between these tags would be seen only by those who share a "staff" usergroup[/staff] while regular members wouldn't see, and it's similar with the [member] tag.
The point of these two special BBCode tags is to allow one usergroup to view whatever text between the tags while not cluttering up a post with information that other usergroups don't need to see (Medicca

Implementing such code shouldn't be that difficult, either, though it's just a simple suggestion.