So I found this thread:
http://www.esoui.com/forums/showthread.php?p=10485
And it seems that the entire ZO_Tooltip class wasnt added until 1.3, as its listed under 'new tables' there.
I then used grep to search the entire lua directory structure for "ZO_Tooltip" (with whole word and case filtering on), and the only files that reference this class are gamepadinventory.lua and gamepadskills.lua, so I was actually correct - this class is a work in progress for gamepad support and isnt functional yet. Too bad =(
EDIT: Thanks merlight, didnt see your reply until I had posted! I came to the exact same conclusions!