Jelmer Tiete has designed a development board for the TI CC2538, that is available at GitHub:
It’s a nice little system-on-chip with an ARM Cortex M3, 2.4 GHz 802.15.4 radio and it runs at 32 MHz. Perfect for all your favorite Internet Of Things (IOT) shenanigans. Contiki supports this chip pretty well, which means easy 6LoWPAN, RPL and CoAP support.
Texas CC2538 based development board – [Link]