My colleague is programming Wireless Sensor TelosB which only can be programmed via the open source Linux operating system. TelosB has printed copper antenna, temperature, light and humidity sensors and can be powered by usb or 2 AA alkaline batteries. Which is also compact in size, approx 2cm by 5cm.
He is using the transciever part aiming to control IROBOT ROOMBA vacuum cleaner via mobile and computer.
Here is a Roomba review