That session happens to be about OS X kexts yes, but it's just where that piece of info happened to slip out. Clearly they've been planning to do at least that much for quite a while now. I wouldn't be at all surprised if they start using a completely separate system partition on OS X like they already do on iOS now.

As far as I know the release versions of the iOS kernel don't support kext loading at all. Most likely, MFI participants are encouraged/required to use standard interfaces or request inclusion of specific functionality if it isn't there already.