Microsoft game console name copied Sony Playstation

From this post, it seems the successor of Xbox 360 should have somethine relate to triangle.

http://forum.unity3d.com/viewtopic.php?t=61839

If the see the picture of Playstation controller, all generation of Playstation controller has button "X", square, circle, and triangle.

http://commons.wikimedia.org/wiki/File:PlayStation_Controller_transparent.png

Microsoft name is first game console with the button "X", and the , so it name XBOX.
The successor of XBOX took the circle button, since circle is 360 degree, so the current Microsoft console is Xbox 360.