The FIFA (Federation Internationale De Football Association) tested successfully an Adidas Soccer ball with an integrated microchip.

The microchip is used to signal when the ball is passing the goal line. The chip sends out an encrypted radio signal to several antennas. The chip inside the soccer ball measures 15mm. Soccer players cannot find a difference to standard soccer balls.
The intelligent ball will be tested next in Japan. Maybe it will be used at the Soccer World Cup in Germany 2006. More details on Reuters UK.

The photos shows Pille, a talking soccer ball, which is one of the mascots (besides Goleo) for the World Cup in Germany next year.