ARM microcontrollers are slowly taking over 8-bit micros like AVR or PIC. In many cases they are much cheaper and offer greater performance. Open source and free tools are getting more robust so programming ARM Cortex became even simpler. This is probably why we see lots small ARM based development boards of any flavor.
Zapta has also built pretty small (38.1mm X 19.7mm) ARM Pro Mini board based on NXP ARM Cortex-M0 microcontroller. Its small form factor allows integrating it in to various size projects while keeping maximum functionality and connectivity. It can also be used in solder-less breadboard prototyping. To make things simpler, he prepared board level library to work with interfaces. Few program demos will help to get started pretty fast.