Starting at just left of the top, and going clockwise:
+3.54V
GND
A0 - analog input
A1 - analog input
A4 - analog input
A5 - analog input
GND
+3.54V
0 doesn't do anything
1 is +3.54V
2 is digital I/O as pin 2, I've only tried O
3 - digital I/O as pin 3 with PWM output (you can analogWrite to it a value 0-255)
I figured out that pin 3 is pwm only because it's used that way in the motor shield demo on this site.
I'm guessing the board is not working correctly, it seems like 0 and 1 should be digital I/O as well.
I tried some simple variants of the blink sketch to try and understand the board schematics (this is my first Arduinoish device).
I agree that tab zero does nothing - it seems to be continuously powered.
The tab marked 1, 2, and 3 are referred to by the same numbers, so to make an LED blink when connected to tab 1, replace the "int led = 13;" with "int led = 1;".
I hope this is helpful for others. Now I need to learn how to do the same thing with the analogue pins.