The Micro Bit is the new Arduino-like electronics venture from the BBC, who will be giving 1million UK kids one of these bad boys before later they go on sale. That in itself could be a worry to Arduino (though Arduino is surely not going anywhere, they have had their distracting problems of late with legal wrangling).
While the device doesn’t seem to have the IO of the Arduino but it does have an LED matrix, Bluetooth LE, and a magnetometer/accelerometer.
Also interesting is the IDE is web based, like Codebender, it seems. This will mean no software maintenance issues?
In the 1980s the BBC had a great success with the BBC Micro getting a generation of kids access to computing, and along with the Pi this could be a popular platform just because of the support it will get.