A basic Sun SPOT kit contains three SPOTs including one basestation SPOT that can be connected to the host workstation and two free-range SPOTs. SPOTs can communicate with each other by wireless technology. There are some LEDs on these SPOTs that can be controlled by Java applications or indicate current working status.
The Air Text Demo
1. Open the demo project by Netbeans IDE and compile it
2. Deploy this demo to one of free-range SPOTs
3. Shake this SPOT from left to right(check the following picture[2])

[1]Quoted from http://en.wikipedia.org/wiki/Sun_SPOT
[2]Copied from http://sunspotworld.com/docs/Green/Tutorial/AirText.html