Mac OS X 10.6: If the indicator light is flashing on your Apple wireless keyboard or mouse
When your Bluetooth enabled Apple wireless keyboard or mouse is turned on, the indicator light flashes twice in succession, and then repeats (blink-blink-pause, blink-blink-pause). This means the keyboard or mouse is discoverable by your computer and you can pair with it. After three minutes, the indicator light turns off. The keyboard or mouse is still on, but it is no longer discoverable. To make it discoverable again, turn it off and then turn it back on.
When the wireless keyboard or mouse connects with your computer, the indicator light glows steady for 3 seconds before it turns off. This indicates that the keyboard or mouse has successfully paired with your computer.
While your mouse is connected to your computer, the indicator light blinks at a regular interval. It could blink fast or slow, but in all cases a regular blinking pattern means the mouse is connected to your computer and is operating properly. The wireless keyboard indicator light does not blink after it has made a connection to your computer.
If you are using a wireless Apple Mouse, the indicator light doesn’t blink.