Free Zigbee Stacks:
FreakZ-Open-Source-Zigbee Stack
BITCLOUD-ZIGBEEPRO
Atmel IEEE 802.15.4 MAC
Atmel Lightweight Mesh software stack
Aurduino Shields/Projects Compatible with DivBee® Modules
http://freaklabs.org/index.php/chibiArduino.html
http://www.souliss.net/p/downloads.html
INFORMATION LINKS
DivBee®