Has anyone looked at a TI SensorTag?

Joel Finkle

Bluetooth Low-Energy (not WiFi)

Coin cell battery with 8uA current draw

 temperature, humidity, pressure, accelerometer, gyroscope and magnetometer

$25

Designed for integration with phones - currently iOS

http://www.ti.com/ww/en/wireless_connectivity/sensortag/index.shtml

Christopher Masto

I have one of these.  It's a demo board for their bluetooth 4.0 platform.  The obvious difference in technology is that Twine's use of WiFI means it has significantly more range and versatility, at the cost of eating batteries like crazy.