IEEE 802.15 concentrates on wireless PAN for a variety of purposes:

• Task Group 1a - WPAN 15.1 Revisions to Bluetooth (R) v1.2 published 2002 June 14
• Task Group 2 - WPAN interoperability so that all those devices in the 2.4GHz don't interfere with each other, i.e. coexistence of 802.15 and 802.11 [WiFi] devices
• Task Group 3a - WPAN Alternate High Rate MAC and PHY
• Task Group 3b - WPAN 15.3 Maintenance
• Task Group 4a - WPAN Alternate Low Rate MAC and PHY
• Task Group 4b - WPAN 15.4 Revisions and Enhancements
• Task Group 5 - WPAN Mesh Networking

UWB and WiMedia fall into 802.15.3 - There is no standard approved as yet. Proponents of UWB have been claiming for years that they will kill off Bluetooth - but there are neither products nor standards on which to base products. WiMedia wants to connect your [TiVo or Windows or... remember Sun Jini?] media center computer to your TV, stereo, etc. But 802.11 a or g or upcoming n do a great job of that.

ZigBee (TM) falls under 802.15.4 and finally had its standard approved on 2004 December 14. But if you check out ZigBee.org, there are still no products. ZigBee concentrates on low-power, low-duty-cylce needs replacing feedback loops for control circuits and sensors. According to their web site, their initial markets include home control, building automation and industrial automation.

Compare these lack of products with WiFi, other 802.11 derivatives and Bluetooth where products generally are announced in advance of the standards being ratified, with compliant products being announced near simultaneously with standards announcements. Bluetooth and WiFi have their markets identified and fill consumer needs or desires. ZigBee comes closest to doing this with its focus on sensors and controls requireing only a low duty-cycle, and I'll do a further study on ZigBee soon. But without clearly defined user needs, these standards are unlikely to make much of an impact in the marketplace.