XBee modules are embedded solutions providing wireless end-point connectivity to devices. These modules use the IEEE 802.15.4 networking protocol for fast point-to-multipoint or peer-to-peer networking. They are designed for high-throughput applications requiring low latency and predictable communication timing
XBee 1mW PCB Antenna (XB24-API-001) is an XBee module from Digi which has a PCB antenna, 1mW output and 100m range. These modules allow a very reliable and simple communication between microcontrollers, computers, systems, really anything with a serial port! Point to point and multi-point networks are supported.
Series 1 and Series 2 XBee modules have the same pin-out. However, Series 1 modules cannot communicate with Series 2 modules
Bildr Tutorial: http://bildr.org/2011/04/arduino-xbee-wireless/
Digi Examples and Guides: http://examples.digi.com/
X-CTU Software: http://www.digi.com/support/productdetail?pid=3352