At the bottom end, the Pi (still $35) and the Chip ($9) are now competing with a new product from Intel called the Arduino 101. If you've been playing with this technology, you'll recognize the Arduino name - they've been around for a few years in the "maker" space. In the past they've used the ATmel/ATmega microchip. Now Intel has announced one that uses the Intel Curie Compute Module, a 32-bit Intel Quark microcontroller.
It comes with 384 kB of flash memory, 80 kB of SRAM an integrated DSP sensor hub for signal processing. The processor includes on-board Bluetooth low energy communications and an accelerometer/gyroscope. The board uses the same form factor as Arduino and has similar I/O capability and it will sell for $30 when it comes out 1Q16.
The programming model is the same as Arduino: you write your code using the Arduino IDE and upload it to the board to run. You'll note that it's much (much) smaller in terms of capacity than a Raspberry Pi, but the coding model is also much more accessible for new developers. They really are quite simple to program.
Intel and Arduino are using it to promote their "Arduio 101 in the Classroom" program - similar to the mission of the Raspberry Pi people.
I think it's exciting to see additional competition in this space as it encourages more young developers to enter the IoT space.