The little square should be just under the left hand of the user whether you hold the device horizontally or length wise.
Perhaps it is actually to do with the Vitality Sensor, and it will allow monitoring of heart rate or something. Its certainly got nothing to do with haptic feedback, or what ever that other rumour was.
“When we make some new announcement and if there is no positive initial reaction from the market, I try to think of it as a good sign because that can be interpreted as people reacting to something groundbreaking. ...if the employees were always minding themselves to do whatever the market is requiring at any moment, and if they were always focusing on something we can sell right now for the short term, it would be very limiting. We are trying to think outside the box.” - Satoru Iwata - This is why corporate multinationals will never truly understand, or risk doing, what Nintendo does.
