I'm not sure at all about Zigbee. A lot of talk and hype but no product.
I have to agree with Roundy. I was also very excited about Zigbee when I first read about it, however, the large number of companies that are "Members" of the ZigBee Alliance is not necessarily a good thing. There have been groups like this in the past and nothing ever really came of them. I look at it as "too many cooks..." type of thing.
From the products I on the market so far, it looks like ZigBee may have a better chance of life in the commercial building sector first. The products may eventually trickle down to the DIY type of user but installation would have to be easy.
It seems like the standards that have really taken off were primarily driven by one company in the beginning; X-10, PLC (UPB) etc... For this reason I give Insteon a better chance for the near future. I am still lobbying for UPB support and I think Matt is considering it.
The other thing Insteon has going for it is the backwards compatability with X-10. Look how many people on this forum are slowly changing over without having to outlay a bunch of cash all at once. X-10 claims over 10 Million users; that's a nice base to tap into.
I am really glad to see Insteon support on the Mac. I've read that the only other serious Mac HA application is still waiting to see what happens with Insteon. Indigo users are fortunate to have such a proactive, involved developer. I have not yet been able to test Indigo 1.8 because my HA Server died after a power surge/blackout the other day.

I am looking forward to testing it out, when I get a new machine.
I'll be at CES 2006 and will be stopping by the ZigBee Tech Zone to see just how far they are.
I would be very curious to find out what you see at CES. Please update us if you have a chance. Have fun, I'm jelous.
Scott M.