Today Shigeru Miyamoto has confirmed that Pikmin 3 really is being worked on and that it will be at this years E3.
Miyamoto confirmed Pikmin 3 during an interview with El Mundo, a Spanish newspaper. Nintendo then reconfirmed saying, "In a recent interview, Mr. Miyamoto confirmed that a new Pikmin game will be shown at the E3 Expo in June. He believes that anyone who has played Pikmin games in the past will enjoy playing."
E3 will begins this year on June 5, 2012.
[Discuss this on the forums.]
The title says "Pikmon". Might wanna fix that.