Here is excerpt from Arduino FAQ >> What should I call my boards? (http://arduino.cc/en/Main/FAQ) :
"Arduino" is a trademark of Arduino team and should not be used for unofficial variants.
While unofficial products should not have "Arduino" in their name, it's okay to describe your product in relation to the Arduino project and platform.
Okay:
- Xxxxxx for Arduino - products that work with official Arduino boards (e.g. shields or kits)
- Xxxxxx (Arduino-Compatible) - variations and clones which are software and hardware compatible
I am not a lawyer ;). But from reading the FAQ, while we can not use Arduino in the name of unofficial product. It can be used as description in above fashion.