[commentereleven]

The main devices that Google devs use - Nexus devices - do not have a menu button.

And I guess they think that the three dot menu is ugly or something.

[72deluxe]

It is automatically created in the action bar when the action area is too small for buttons:

http://developer.android.com/design/patterns/actionbar.html

http://developer.android.com/guide/topics/ui/actionbar.html