if there is a cd in the drive you might be able to get it out by using open firmware simply:
Hold down Cmd-Opt-O-F (during start up) then at the prompt type
eject cd
mac-boot
or try holding the mouse button down during start up will force eject the cd.
i have had once a stuck cd (did not eject at all not even the people at the genius bar could get it out) a service tech at the apple store replaced my combo drive with a new one.