What is ZigBee? What is IEEE 802.15.4? How is ZigBee different from other wireless standards (e.g. Bluetooth)? What are the real-life applications of ZigBee? How reliable is the data delivery? How long is the battery life? What are the cost considerations for ZigBee implementation? How long is the Transmission Range? How high is the Data Rate? What is the Data Latency for ZigBee Networks? How large/small a ZigBee Network can be? How is the Data Security provided? What is ZigBee Stack? What Subunits can be on a Node? What is called ZigBee Application? What are the ZigBee Device Descriptors? What is ZigBee Device Profile? What is ZigBee Stack Profile? What are the ZigBee Device Objects? How does a Device/Service Discovery process work? What are the Clusters, ZigBee Binding and Binding Table? How is Addressing and Messaging done in a ZigBee network? What types of ZigBee Devices exist in a network? What Topologies are supported by ZigBee? What is ZigBee network Gateway?
Are there yet ZigBee products on the market?
Yes, there are. Some implement an actual ZigBee stack while others feature a ZigBee ready platform like EmberNet.
Examples in the residential space include Control4 (lighting), Eaton (home automation), Golden Power Manufacturing (sprinklers and thermostats), Hawking Technology (home gateways), Kalirel (heating), Mija (fire extinguishers), Nice (shutters), and TSC Systems (home automation).
Examples in the commercial space include Mija (fire extinguishers), Philips (lighting), Siemens (building automation), and TAC (building automation).