Wow, the best way to keep something secret is to show it to the press…..
According to IGN, EA accidentally revealed the rumbling SIXAXIS to the press in its pre-TGS media briefing. The PS3 version of Burnout Paradise had a heftier feel to it: the controller was heavier and had a giant sticker that said "RUMBLE." With the cat out of the bag, IGN also added that "A formal announcement is expected tomorrow at Kaz Hirai’s keynote address." Early word on Kaz’s keynote suggests that other significant announcements will headline Sony’s presentation.
Source: Joystiq