Integrating motion sensing with ZigBee wireless technology, the SPMB250-A1 MotionBee platform from ST lets system developers build wireless sensor networks for remote motion recognition and tracking. The 49 x 27 x 5-mm device has a 3-axis digital-output MEMS accelerometer with an Ember ZigBee set with an EM250 System-on-Chip, a 2.4-GHz, 802.15.4-compliant radio transceiver and processor, with the EmberZNet PRO ZigBee networking software. The module detects accelerations in the selectable range of +/-2g and +/- 6g and transmits the information to a central connection point (star topology) or every other node (mesh topology) in a ZigBee wireless network. Samples priced at $60.
Link to MotionBee SPMB250-A1 - http://www.st.com/stonline/products/families/sensors/wireless_sensor_modules/spmb250-a1.htm