It's great to see 802.15 getting a little bit of press. It's fantastically low power, got pretty good range, and the throughput isn't bad. Far better than 802.11 for these kinds of devices.

For anyone who wants to play with 802.15, I strongly recommend getting your hands on some Sun SPOTs. I've been playing with one of the dev kits, and they're an amazingly hackable platform.