looking for LEGO ultrasonic documentation

[the programmer]

does anyone know where I can find good documentation for LEGO's sonar sensor?

[StevenB]

What specific kind of documentation do you need?

Check out the Hardware Documentation for the NXT system here:
http://mindstorms.lego.com/en-us/support/files/default.aspx

[the programmer]

about the communication between the sensor and the NXT

[Mark McLeod]

Like this (http://team358.org/files/programming/sensors/Ultrasonic_Sensor_I2C_communication_protocol.pdf)?

I got that from Mike Betts.