Arduino – Official boards, Clones, Derivatives, Compatibles and Counterfeits. Big article on Arduino blog, including how to spot a counterfeit board. There’s also a special shout out to our ladyada (and FLORA) & Paul (Teensy) for her work in the Arduino community –

A more interesting segment for us is what we call Derivatives. These are products that are derived from the Arduino hardware design but they innovate either by providing a different layout and features often to better serve a specific market. These are the products that have also helped Arduino become so ubiquitous.
There are many examples but I will mention only a couple:

Teensy by PJRC – Paul has contributed a lot of code, bug reports, pull requests and to the discourse in general.
Flora by Adafruit – Limor has contributed over 100 libraries and countless tutorials about Arduino becoming one of the most important members of the Arduino ecosystem.

Read more.