If you are using an Arduino Mega, SDA is pin 20 and SCL is 21, so note that shields with I2C need to be specifically for the Mega (taken from Tutorial: Arduino and the I2C bus – Part One | tronixstuff.com)
If you are using an Arduino Mega, SDA is pin 20 and SCL is 21, so note that shields with I2C need to be specifically for the Mega (taken from Tutorial: Arduino and the I2C bus – Part One | tronixstuff.com)