Zigbee networking came up as a fairly serious discussion topic and I spent some time with Google. Here is where I document what I learned so I can find it again.
Zigbee is a mesh network standard that operates over IEEE 802.15.4 networking hardware. The software protocol is called Zigbee and it is administered by the Zigbee Alliance (link is to the products page). There are plenty of announced gateways and products out there. I wonder how many are real?
There is a reasonable explanation of the 802.15.4 spec here. At least it looks reasonable to a Zigbee novice like me.
Product Design and Development has a sort of round table on 802.15.4. A comment by Robin Heydon caught my eye:
The technology best suited for consumer products is either Bluetooth low energy, or a combination of Bluetooth with a higher speed radio for transferring large files. Unlike 802.15.4, Bluetooth only needs to be on when it is sending or receiving. During down time the radio is switched off to save power. Bluetooth low energy is designed for products such as watches, sports devices and products that do not need to send large amount of data.
Zigbee comes in various forms including chipset radios that cost about $5 each, near as I can tell. Texas Instruments makes some of these products. Others do as well. Here is a chipset level comparison chart. Zigbee/802.15.4 Chip Comparison Guide.
Trilliant appears to be focused on selling to utilities: Trilliant passes 1 million.
Tendril is the company that got us started thinking about Zigbee.
Tendril explained by Tendril.
Zigbee is an "open standard", but it costs $3500 per year to get the specs. However, there is an in progress truly open source effort that you can read about at freaklabs open source zigbee blog. I think this may be the mother lode for learning about Zigbee. See the Featured Zigbee Articles.
Engaget has a Zigbee tag. Some of these look pretty interesting:
Nokia launching Z-Wave Home Control Center next year
Philips SJM3151 universal remote mirrors your iPod screen
"Tweet-a-watt - our entry for the Core77 & Greener Gadgets design competition" is a Kill-a-Watt(TM) power meter modified to "tweet" (publish wirelessly) the daily KWH consumed to the user's Twitter account (Cumulative Killowatt-hours).
And here are the instructions. There are several links inside. Pretty much anything you need to know is there.
We had a conversation with Hayden Williamson of Digi International, mostly about their X2 ($200), X4 ($400 or $500 depending on options), and X10(?) gateway devices. These are programmable in Python and have about 1 mB of unused memory. It has an Arm processor.
An alternative to Zigbee is GainSpan's lower power WiFi: http://www.gainspan.com/ GainSpan is claim 3 years on one AA battery (versus Tendril's 2 AA).
Another alternative is X10:
And here is a fancy home power meter based on X10 and an IOBridge IO-204 Monitor & Control Module.
I just found a XBee Wiki