Matt Helgeson of Game Informer reports that Shigeru Miyamoto himself mentioned the rumored Zelda Wii U title is in steady, but definitive, development. In fact, they were almost going to show it during today's Nintendo Direct stream.
"We're also working on a new Wii U Zelda game. Work on that is progressing fairly concretely. In fact, we were thinking about showing it here at E3 but decided to wait just a little bit longer before sharing it with everyone."
I'm pretty surprised they didn't show it off today, even if it would have only been just a brief teaser, as I'm sure many Zelda fans would have loved to have seen it regardless.
Hopefully "a little bit longer" isn't too much longer.