Samurai Panda at SmashBoards comes through again.
According to this report (translated from Japanese), Director Masahiro Sakurai attended the Snake vs. Zombie event in Japan. The first line of the third paragraph quotes him:
"[You] have waited quite a long time until now... I guess I should finally release some information soon"
I was expecting some stuff pre-E3, and this makes it sound all the more likely.
On Thursday this week is the one-year anniversary of the unveiling of the game. Will the developers be clever and unveil something then? Things usually don't work that way, but ya never know...