Incidentally that means, so long as your access point broadcasts its WiFi network name, you are also broadcasting (to everyone who can hear it) whether you've opted out. It's not just between you and Apple.
Not to mention that changing your SSID disconnects everything using it.
It just sucks all around.
@BradRubenstein @briankrebs I haven't seen it mentioned yet, but I guess they have to disambiguate Corporate or large WiFi networks by BSSID and MAC? Add another thing to the stack of "I'll dig into this when I get some time."