Runeglaive seems really good for spammy junglers with mana issues like Udyr (which I've had a lot of fun building AP bruiser with). I don't play high-AP junglers very much, so I don't know who else would consider going in the jungle, but it really doesn't seem as bad as people are making it out to be. It's more interesting than Magus was at least.
I was considering Kayle jungle too, but she loses so much health early on I can't find a way to stay on par with my teammates when I play her because her first clear is so terrible.
What about Evelynn, Elise, Karthus, Malzahar, Fizz and Teemo? All of these champions are very fast casters and have some ganking potential (though I imagine Karthus would just use his ultimate to replace ganks and farm otherwise for safety). Do they not have the sustain or tankiness necessary to jungle? That's the biggest potential issue I see.