A friend lost their Apple bluetooth keyboard and Logitech bluetooth mouse.  Bluetooth controls were grey – computer appeared to not see the bluetooth hardware.  They recently updated from 10.5.8 to 10.6.

Solutions was:

MacBook (13 inch, Late 2008), MacBook Pro (15-inch, Early 2008), and MacBook Pro (17-inch, Early 2008)

If the computer is on, turn it off.
Disconnect the AC adapter and remove the computer's battery. ( also disconnect all other cables)
Press and hold the power button for 5 seconds and then release the button.
Reconnect the battery and AC Adapter.
Press the power button to restart the computer

This resets the "SMC" see article  http://support.apple.com/kb/HT1411