Today I had to help a friend force eject a stuck DVD in his iBook, there are a couple of methods we tried and I thought that hey may be helpful for others.
I would recommend trying to eject your stuck CD/DVD in this order;
1) Hold the ‘Eject’ Key for up to 30 seconds.
2) Stop the CD/DVD spinning
Stop the CD/DVD from spinning by gentle pushing in a thin piece of cardboard ( not to soft, nor hard ), thin packaging cardboard from like a battery or toy packet.
This will stop the CD as it is always spinning slightly, then hold the EJECT key for 8-10 seconds.
3) Restart holding the Mouse Button
Restart your mac, and once the machine chimes, hold the mouse button down ( external mouse or trackpad button ). This should eject the DV/DVD in up to 8 seconds.
If not, restart your mac again.
4) Restart in to Single User Mode
Restart your machine, and hold down the ‘Command ( apple )‘ + ‘O ( o for orange )‘ + ‘F ( f for fred )‘ keys.
This will boot you in to single user mode.
Type the following Command:
eject cd
Then press the ‘enter’ key
This should eject the CD/DVD.
Once the CD is ejected, type;
mac-boot
Then press the ‘enter’ key to boot back in to your Mac OS.

Point of clarification: #4 puts you into Open Firmware; this will not work for Intel-based Macs.
You posted this command:
4) Restart in to Single User Mode
Restart your machine, and hold down the ‘Command ( apple )‘ + ‘O ( o for orange )‘ + ‘F ( f for fred )‘ keys.
This will boot you in to single user mode.
Unfortunately that is not correct. The steps you provided are for booting to Open Firmware, not Single user mode. It is not possible to boot to open firmware on any mac with an Intel processor, so these commands are a bit out of date. If you do have a PowerPC, the commands in open firmware will eject your disk.
To boot to single user mode on a PowerPC or Intel mac, hold the Command key (the one on either side of the space bar) and the letter ‘S’. I do not know how to eject the optical drive in single user mode, if you know how to use Unix to open a disk drive, that will likely work here. What single user mode is, is booting to a Unix command line.