If you have ordered “LCD Keypad Shield for Arduino Duemilanove & LCD 1602” from DealExtreme and are wondering about how to get this thing working without datasheet, you are in the right place
This product seems to be very similar(!) a product called “DFRobot LCD Keypad Shield for Arduino” and the Datasheet and even a library (LCD4bit_mod) for easy programming of it is available at following link, http://www.robotshop.com/dfrobot-lcd-keypad-shield-arduino.html, under useful links.
The only issue with the library is that this is built for old versions of Arduino and if one to make it work with newest version (Arduino 1.0), then some parts of the code should change. First you need to install the additional library in your Arduino on your computer (by copying the content of the zip file in the “libraries” folder of Arduino program). Afterwards one should change the content of LCD4bit_mod.cpp