Function of square plug near 12v. plug!

[RS-Yaris]

Anybody know the function of this square plug near the 12v. socket on my 2009 Yaris HB. What is the switch or the socket that replace this square plug in other Yaris or Vitz version.

http://i378.photobucket.com/albums/oo223/syncrov69/Snapbucket/DSC02071.jpg

[wispaintstyle]

That's where usb power would go if you were equipped.

[RS-Yaris]

and do you have any picture of this? easy to install? option for north american market or other country?