I'm more interested in the Leonardo with the 32u4 chip myself. Much smaller than the Arduino, simpler circuit, built-in USB for higher data transfer bandwidth and comes with lots of A/D's. The 32u4 has been _the_ chip for low-cost projects that involve communication with a computer for some time now (Adafruit and PJRC [Teensy] make one), but Arduino is going to bring it to a bigger audience. The Teensy already worked with Arduino libraries, but the boot loader wasn't free and it wasn't 'officially supported'.

There is a big difference between a Cortex-M3 and whatever is powering the Raspberry Pi. It's intended as an 8-bit microcontroller replacement. I've recently switched from TI MSP430 processors to this same Cortex-M3 from Atmel and performance has increased while per unit cost has gone down.

The Cortex-M3 microcontrollers are awesome. Much more powerful than the older 8-bit architectures available at the same price, and amenable to industry-standard tools instead of just the compilers and IDE sold by the manufacturer. I think this move just mirrors the general industry trend toward the ARM architecture. It's become difficult to justify using one of the old 8-bit architectures anymore, except at the lowest extremes of price or power consumption.

Correct. The ARM M series doesn't even have floating point hardware. The M3 is intended for real-time, low power applications, and is indeed a fantastic replacement for 8 or 16bit microcontrollers.

Thanks for the clarification. Is there really much demand for such a board?

I want one, and I know several others that will as well. The 32-bit Cortex-M3 core at 96 MHz leaves an AVR in the dust; it has low-power modes that make power consumption comparable; and the peripheral set advantage of the AT91SAM3U over an ATmega is huge.

Also, ARM Thumb2 is a much nicer instruction set than AVR in my humble opinion. Cortex-M3 also has some great instructions to improve the efficiency of real-time preemptive kernels (e.g. RBIT, CLZ and automatic pushing of registers on interrupt). I've written my own tiny kernel for this microcontroller, and I'll definitely be putting it up on github since this release increases the likelihood that others will contribute to it.

Also, Cortex Microcontroller Software Interface Standard (CMSIS) [1] makes porting between vendor's offerings (e.g. STM32 or Stellaris) much easier than going from say AVR to MSP430.

[1] http://www.arm.com/products/processors/cortex-m/cortex-micro...