This is one of these cheap Arduino Nano clones that are sold on Ebay for something around 2 USD. The main difference between the original and the clone is the USB to serial conversion chip. The original uses the popular FT232, but the clone uses CH340G - a cheap USB-UART converter. The cost of this Chinese chip can be under 0.5 USD / piece.
Schematic diagram (click for full resolution)
Top side (click for full resolution)
Bottom side (click for full resolution)
This board works more or less as expected, it's basically the same thing as the original (the main IC - ATmega328 - is the same on both boards). The USB interface seems to work OK, at least on Linux (no extra drivers were required), but I got some problems with baud rates higher than.
A small problem with (as far as I know) all Arduino Nanos is the fact that there is no fuse on the USB port. +5V from the USB port is connected through a Schottky diode to the Arduino's +5V rail. This diode will prevent current from flowing back into the USB port. When overloaded, the diode will fail, either going short or open circuit (that's not a big problem to debug) or it will start behaving like a resistor, which can be very annoying and take some time to find. It also causes the voltage to drop a bit (0.2V under low currents up to 0.5V depending on the exact diode type). The original diode on my board was an MBR0540 (or 0520, which is a little bit better. It has lower maximum reverse voltage, which doesn't really matter, because there is only 5V anyway, and also has a lower voltage drop.) I replaced the old burnt diode with a new MBR0520 (several times already) and it works fine.