I have always thought they used the GPL when releasing the Arduino core and libraries but actually after reading their website I realized they are using LGPL, not GPL. This has some implications that I'd like to discuss here since we develop software mostly based on their core and libraries on this subforum.
Read under "what do you mean by open source hardware".
With LGPL lisence, only the Arduino portions (core and libraries) of a project are under GPL (General Public License). The code developed by a third party, you, me, others, can take any license we want, including closing the source. This means you may develop a project and decide to make the code closed source and copyright it then try to sell it for money or license it out.
This may have both ups and downs. The down side is very clear. Someone uses the platform and develops something good and then closes the source and others may not see how the project is done or learn from it. The up side though, is someone having an idea trying to use Arduino will be assured that their time and resource spent developing their projects using will be copyrighted so they may protect their investment. This someone could be large corporates or individuals. This could encourage such entities with concerns of open source to get on board with Arduino.
In any way, if they used Arduino, they need to acknowledge Arduino portion and can't just say they made the project single-handed.
Any comments? Corrections?
I am preparing to release an Arduino-based platform with possibly CC-BY-SA on circuit board (I didn't start from Arduino design file), and the firmware with GPL. But I don't want to be taken advantage of. I might have to play the license game.