I was successful in getting an NXT (using Robotc) and an Arduino to talk to each other over I2C but there was a problem I hit that I did not expect.
I found that if I included Serial.print statements in my onRequest handler the data being sent to the NXT master would be "mangled". I have confirmed this with a Saleae logic analyzer and can easily reproduce this problem.
It appears others 'might' have had this issue. When I searched the forum there were some unanswered posts from people who were having similar problems (for example http://arduino.cc/forum/index.php/topic,90516.0.html ).
Is it possible to update the Wire.onRequest library documentation page to warn people about this issue? (Or is this common knowledge and I just didn't know about it? :grin: )