DFRobot just released the first Nano sized Leonardo- Dreamer Nano
The Dreamer Nano V4.0 is a surface mount breadboard embedded version of the ATMEGA 32U4 with integrated Micro USB. It has everything that Leonardo has (electrically).Physically, it is just missing power jack to save space.
Using the ATmega32U4 as its sole microcontroller allows it to be cheaper and simpler. Also, because the 32U4 is handling the USB directly, code libraries are available which allow the board to emulate a computer keyboard, mouse, and more using the USB-HID protocol!
The Dreamer Nano v4.0 is compatible with most Nano shield in the market. It's suitable for projects that require a compact size controller system.
I bought one a while back and quickly ran out of uses for it - unless there's a way of sending a signal to it, eg (like the guy with V-USB) pressing the caps lock 3 times invokes a function, but I have no idea at all how you apply what the V-USB library does to one of these devices (That includes the Leonardo and clones)