The Embedded Pi is an interesting board as it combines Raspberry Pi, Arduino and STM32
CooCox has disappeared at this point, and the RPi support is for the original rather than current offerings, but still a board one could mash together a clean and concise proof-of-concept, or small test deployment.
I'm left pondering what in the world Newark/Element14 is going to do with nearly 3200 boards? The price keeps dropping (~$25 now) but it is not low enough to move them yet, $5 perhaps?
ST-LINK connectivity can be achieved with a MikroProg adapter
Useful things that set it apart from a NUCLEO:
Regulated 5V from 7-20 VDC external supply via barrel connector
Diode protection into Arduino VIN pin
USB Connectivity to the STM32
ISP/SPI Arduino pins
Full JTAG capable, SWV support by default